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1. The event has been handled return this Like all other statements the switch statement may also be nested var uint8 bitField switch bitField amp 0x03 case 0x01 case 0x02 switch bitField amp OxF0O case 0x10 case 0x20 0x30 0x40 case 0x50 default default 5 8 for iteration statement The for iteration statement executes an expression and a statement repeatedly until the value of the expression is false The syntax for the for statement has two forms Form 1 for condition loop expression Statement Form 2 Embedded Wizard Copyright TARA Systems GmbH Page 94 Chora User Manual www embedded wizard de Statements TARA Systems for init expression condition loop expression statement There is no restriction on the type of init expression and loop expression The condition expression must be of type bool otherwise the Chora compiler returns an error Execution of a for statement proceeds as follows 1 The init expression if any is evaluated This specifies the initialization for the loop The init expression is evaluated only once at the time the for iteration statement is begun 2 The condition expression is evaluated It is evaluated before each iteration 3 If the condition is true the statement is executed and then the loop expression is evaluated The loop expression is evaluated after each iteration The process then starts again with the evalu
2. The variable theView is out of scope here theView lt Will cause syntax error If necessary compound statements may also be nested for counter 9 counter gt 0 counter counter 1 var Core View theView views counter if theView Visible theView Bounds lt 0 0 100 200 gt theView Visible true If a compound statement contains no embedded statements it is a special case of the empty statement This statement is simply ignored and not executed at runtime if menu Visible true Nothing to do here 5 6 if selection statement The if statement allows conditional execution of a statement or a conditional choice of two statements executing one or the other but not both The syntax for the if statement has two forms Form 1 if expression statement Form 2 if expression statement else statement Embedded Wizard Copyright TARA Systems GmbH Page 90 Chora User Manual www embedded wizard de Statements TARA Systems In the first form of the syntax if expression is true statement is executed If expression IS false statement is ignored In the second form of syntax which uses else the second statement is executed if expression is false With both forms control then passes from the if statement to the next statement in the logic The expression must have type bool or a Chora compiler error occurs The following example uses
3. Item item Sample Menu item Ok theView item Ok theGroup item Ok theItem item theMenu null Because of Chora s polymorphic character it is possible at runtime for one and the same variable to point to objects of different classes The object cast operator is then superbly suited to evaluating the inheritance hierarchy of such an unknown object In this way it can be determined at runtime whether the unknown object is indeed derived from a given class before the object is accessed Embedded Wizard Chora User Manual Copyright TARA Systems GmbH www embedded wizard de Page 136 Operators TARA Systems var Core View theView Sometimes theView points to a Sample Item object and sometimes it points to Sample Menu object if someCondition theView new Sample Item else theView new Sample Menu Hmm we are not sure Is theView a Sample Item object if Sample Item theView null Yes So it is safe to access this Sample Item object without any problems Sample Item theView ITtemCaption Settings Or is theView a Sample Menu object if Sample Menu theView null If true it is safe to access this Sample Menu object Sample Menu theView ShowMenu Use of the object cast operator in an if condition thus ensures that access to the object w
4. c 0x154AA00 Bitwise and The result is the bitwise and of both operands var uint32 a OxFFOO3ACO var uint32 b OxABIL5FF70 var uint32 c c a amp b c 0xAB003A40 Rectangle intersection The result is a rectangle that represents the intersecting area of the both rect operands If the intersecting area is empty the operator returns an empty rectangle var rect a lt 10 5 110 220 gt var rect b lt 10 50 50 75 gt var rect c Se SS br e lt 10 5 50 75 gt Intersection of two styles sets The result is a new Copyright TARA Systems GmbH Page 127 www embedded wizard de Operators TARA Systems amp set amp set int Pint rect rect ge 7int Pint Embedded Wizard Chora User Manual styles set which contains the style names enclosed in both operands var styles a Aqua Win95 var styles b Win95 var styles c c a amp b c Win95 Intersection of two sets The result is a new set which contains the enumerators enclosed in both operands var Unit Align a var Unit Align b var Unit Align c Unit Align Top Left Unit Align Top Gs a amp b c Unit Align Top Bitwise inclusive or The result is the bitwise or of both operands var uint32 a OxFFOO3ACO var uint32 b OxABIL5FF70 var uint32 c c a b c OxFFISFFFO Rectangle union The result is a rectangle that represents the union area of the
5. gt Declaration statement gt Allows the programmer to declare local variables and arrays within the body of a method Locally declared variables and arrays serve to store intermediate results when executing the logic of a method gt Expression statement gt Determines the value of an expression The expression consists of a sequence of operands and operators gt Empty statement gt The empty statement does nothing It is useful when the syntax of the language expects a statement but no expression evaluation It consists of a semicolon gt Compound statement gt A compound statement also called a block typically appears as the body of another statement such as the if selection statement A compound statement combines several statements into a single one gt if selection statement gt The if selection statement provides a means of conditionally executing sections of code The statement controls conditional branching The body of the if selection statement is executed if the value of the condition is true gt switch selection statement gt The switch selection statement helps control complex conditional and branching operations The switch selection statement transfers control to a statement within its body depending on the expression in the switch statement gt for iteration statements gt The for iteration statement lets you repeat an other statement a specified number of times The body of a for iteration statemen
6. var bool oc c a isempty c false c b isempty c true This instant property is read only You can t assign any values to isempty int32 point x The instant property x corresponds to the X coordinate of the point The read access to this property returns this coordinate value and the write access changes it The other coordinate value Y is not affected var point a lt 10 20 gt var int32 c Get the x coordinate c ais c 10 change the x coordinate a x 0 a lt 0 20 gt int32 point y The instant property y corresponds to the Y coordinate of the point The read access to this property returns this coordinate value and the write access changes it The other coordinate value X is not affected var point a lt 10 20 gt var int32 c Get the y coordinate c a y c 20 change the y coordinate a y 0 a lt 10 0 gt bool styles isempty The instant property isempty is used to determine whether a styles set is empty or not An empty styles set does not enclose any style names Embedded Wizard Copyright TARA Systems GmbH Page 154 Chora User Manual www embedded wizard de Operators TARA Systems var styles a Aqua var styles b var bool Cy c a isempty c false c b isempty c true This instant property is read only You can t assign any values to isempty bool set isempty The instant property isempty is used to determine wheth
7. var point Offset lt 48 50 gt A point stores the value of each x and y coordinate as a 32 bit signed integer Structure containing the x1 y1 X2 y2 coordinates of a rectangle The coordinates of a rectangle are always enclosed in angle brackets and separated by a comma Bounds lt 0 0 120 64 gt Frame lt 10 20 40 55 gt Var regi Var regi A rect stores the value of each coordinate as a 32 bit signed integer Language variant data type A variable of type language stores the name of a language variant The name used for the language must be defined within the project file var language currentLang German var language defaultLang Default The data type language is used when switching between languages and in resolving language dependent resources and constants The user can store the name of a language variant within a local variable evaluate the value of this variable use it to switch between languages etc Aside from the data type language there exists an identically named global built in variable that stores the name of the currently selected language variant Details on switching between languages can be found in Language selection chapter 9 Styles set data type A variable of type styles can store a list of style names The list is enclosed in brackets and the names are separated by comma signs An empty styles set consists of empty brackets only var styles temp Aqua
8. Caption only Anyway the origin constant is influenced by the variant the default value of the constant is overridden so at the runtime the evaluation of the origin constant will result in the string Hello variant Embedded Wizard Copyright TARA Systems GmbH Page 179 Chora User Manual www embedded wizard de Usage of Variants TARA Systems var string text This expression will cause Chora compiler error because the variant can t be accessed directly text MyMenu MyCaption Access the constant Since the constant is overridden by a variant the expression results in the value of the variant itself text Menu Caption text Hello variant The variant defined in the example above is called static because the variant substitutes the origin constant permanently it can be switched neither during the code generation nor at the runtime it is fixed More flexible variants expect an additional variant condition directive This directive determines when the affected variant will be used For example if the variant MyCaption should be used in case of selected Win32 profile only the name of the profile should be specified in the variant condition S variant Win32 veonst MyCaption Menu Caption Hello variant In this case the origin constant is not substituted unless the code is generated for the profile Win32 If the profile specified in the directive does not exist in the pro
9. Embedded Wizard Copyright TARA Systems GmbH Page 87 Chora User Manual www embedded wizard de Statements TARA Systems array float points 16 var int32 inx Initialize all items of the array with 0 0 for inx 0 inx lt 16 inx inx 1 points inx 0 0 The validity of an array is limited to the block in which it was defined Within this block the name of the array must be unique Identically named arrays may not be defined within one and the same block For this reason the following code causes a Chora compiler error message if al gt a2 array int32 tmp 4 if al a2 array int32 tmp 2 The definition of an array can occur anywhere in the logic of a method where statements are allowed Thus it is possible to define an array even in the middle of a block Note that the content of an array is lost when the block is left As a result it is not possible to define global or static arrays All arrays are automatically defined when the block is entered and removed if it is left Additionally it is possible to define an array consisting of more than one dimensions For this purpose the sizes of all dimensions have to be placed between the braces and separated by commas array int32 Field 4 5 The access to a multi dimensional array works in the same way as the access to a single dimensional array The index of the required array element consists of more expressions separated b
10. Item Bounds x2 Item Bounds x2 16 When an assignment is made to a variable or to an array item the result of the assigned expression is copied directly into the memory of the variable or the array When an assignment is made to a property the onset method of that property is always invoked with the result of the expression as its hidden value argument The new property value is not copied to the memory at that time Only in the onset method the programmer can decide what should happen with the assigned value Details of the onset method may be found in onset methods chapter 4 1 5 3 The Chora assignment operator subjects the result of the expression to an implicit automatic type conversion if the data type of the expression does not match the data type of the variable property or array var Core View Menu Menu new Sample Item The above assignment therefore uses an implicit type conversion in order to convert the expression from data type Sample Item to Core View The same result can be achieved by using an explicit typecast operator var Core View Menu Menu Core View new Sample Item The implicit type conversion follows the same rules as the explicit typecast operators described in Instant cast operators chapter 7 3 and Object cast operators chapter 7 4 Embedded Wizard Copyright TARA Systems GmbH Page 158 Chora User Manual www embedded wizard de Operators TARA Systems 7 12 parentth
11. KE TARA Systems sx Embedded win Wizard Le Chora User Manual deng Itako nur OBQB ALLY ab eog mer se Blo Shox ar si AA D r e a Ka Bue x Es Joson we I YO ret pE th Maton ma L rl N T 5 testas State user dete is zait Signal OnstatecRanged Size a Sinerbate ClentFrammaock tert ter viewsTest tiaga ication aaserData Testingine wein test screens new ViewsTest siTestSoreens mew ViewsTest riTesticreens Loading ririnucs an de w At the firat tost screen C NEmbedsedwiz ard Testt work Testfr worrie oter d z Reet Maal Sereen As eT ee ee ee ME EE D viewsTest stool ication userdata Logsted gt Led ee mg Version 6 51 28 April 2015 Authors Dipl Ing Paul Banach Dipl Ing Manfred Schweyer Copyright c TARA Systems GmbH Copyright TARA Systems GmbH www embedded wizard de Introduction TARA Systems Contents Chora User Manual www embedded wizard de 1 Introductio EE 4 2 Programs in LE 7 3 Project tle EW E 9 ED AT E E E E E EA TE E A A EA E TE E E ON 9 3 2 Profiles and Nr ET 10 33 We E E 15 Se leese Eege eege E 16 SEELEN 17 BB Elle 18 4 Unit file EWU c cssccasceewessenewensdaeisnenedeoes coadetbcaveanenscesdlatnesnsbenttarwesecament 19 D Rer 20 4 1 1 Instance variables ccceecececccececsesnesececeeccseseeaeeecesecscseseaaeeeceesceceeseeseseeeeseecseseaaeseeeeseeesesseaees 23 A12 molane ay CT 26 A Melu 29 4 1 4
12. method void DrawLine arg point aStart arg point aEnd Do something to draw a line from aStart to aEnd point Embedded Wizard Copyright TARA Systems GmbH Page 37 Chora User Manual www embedded wizard de Unit file EWU TARA Systems If a method expects more than one argument all the arguments must be separated by commas at the time the method is called The following example demonstrates how the method DrawLine has been called with two points lt 10 20 gt and lt 100 120 gt as arguments var Sample Shape shape new Sample Shape shape DrawLine lt 10 20 gt lt 100 120 gt A method does not necessarily always have to expect arguments In fact it often makes sense to define methods without arguments In such cases the list of arguments is omitted in the definition and when the method is called What remain are the parentheses class shape method void Show Do something to show the graphical object If a method is called with the wrong number of arguments or the data type of arguments given do not match the definition of the method anywhere the Chora compiler will report an error message and the translation will be aborted If the return value of a method is not void the method must always return a value The appropriate statement return then terminates the method and returns value to the caller class Math method int32 Power2 arg int32 aValue return aValue
13. 0x000D CR Carriage return Xt 0x0009 HT Horizontal tab v 0x000B VT Vertical tab 0x005 Backslash KA Ox0027 Single quote 0x0022 Double quote GE dd OKEHE Character in 4 hex digit notation 0 0x0000 Null Character For example to terminate a string with the new line character the following escape sequence could be applied var string text Hello World n color True Color value in the 32 bit RGBA red green blue alpha format The red green blue and alpha components of a color are expressed in hexadecimal notation behind a number sign var color Black 000000FF var color Yellow FFFFOOFF var color DarkBlue 000050FF var color Red FFOOOOFF var color Transparent 00000000 The first two digits of a color define the red component The green Embedded Wizard Copyright TARA Systems GmbH Page 114 Chora User Manual www embedded wizard de Data types TARA Systems point rect language styles component follows then the blue and finally the value of the alpha component Each component is defined using two hexadecimal numbers in the range 00 to FF If the alpha value given is 00 the color is transparent independent of the red green nor blue values Structure containing the x y coordinates of a point The x y coordinates of a point are always enclosed in angle brackets and separated by a comma var point Origin lt 0 0 gt var point NextPosition lt 20 38 gt
14. Begin 0 Enabled true EndValue FFFFFFFF Endless true Factor 3 x Class The class name of this object Embedded Wizard expects here the name of a class in order to be able to create the sl Description a 4 1 5 Methods Methods are always introduced with the keyword methoa followed by the return data type the method name argument list and the logic the body of the method class Menu method void HandleFocus arg bool aObtain if aObtain Do something in response to the obtained focus ete This example shows the definition of a class Menu with a single method HandleFocus The definition of the method determines precisely how it is to be used when it is called Thus this method expects nothing other than one argument of type bool The method s return type has been given as void meaning the method can t return a value The Chora language offers various data types that you can use in defining a method You will find further details in Data types chapter 6 Embedded Wizard Copyright TARA Systems GmbH Page 36 Chora User Manual www embedded wizard de Unit file EWU TARA Systems The method s logic is enclosed by two braces Here the programmer defines which statements are to be executed when the method is invoked He can use conditions loops local variables expressions etc You ll find further details in Statements chapter 5 Calling a method always occurs in the c
15. Embedded Wizard Copyright TARA Systems GmbH Page 184 Chora User Manual www embedded wizard de Garbage collection TARA Systems 11 Garbage collection Garbage collection is a special feature of the Chora programming language It relieves the programmer of the responsibility of having to explicitly delete unused objects The Garbage Collector determines unused objects and automatically takes care of their disposal This eliminates one of the most feared sources of programmer error for thanks to garbage collection it is no longer possible for dynamically created objects to be destroyed more than once or to remain undesirably in memory as memory leaks How the Garbage Collector works actually depends on the target system In general however a Garbage Collector works in 2 phases gt Phase 1 Mark During the first phase the Garbage Collector attempts to locate and mark all objects that are still needed All objects thus marked are then protected from deletion During the marking phase the Garbage Collector traces all the connections between the objects and thus marks every object it can reach The process ends when all reachable objects have been marked The starting point for the route taken by the Garbage Collector is a so called root set that is one or more objects that exist during the entire lifetime of an GUI application and which correspondingly may not be deleted gt Phase 2 Sweep In the second phase all objects not marked
16. Statements TARA Systems In the same manner as it has been demonstrated in the examples above a slot method can also be attached as observer for notifications triggered for an object In this case the attachobserver statement expects an expression which results in an object attachobserver update controller After this operation the update slot method is able to receive post signals each time the notifyobservers statement triggers the object controller notifyobservers controller If one of the expressions specified in the attachobserver statement results in a null value the observer is not registered and the program execution is continued without any error messages var slot theSlot null var object theObject null attachobserver theSlot theObject This should not be mixed with the third form of the attachobserver statement where the null value is passed explicitly as the second operand of the statement This form of the statement is designed especially for the registration of global object and property independent observers attachobserver update null As the example above demonstrates the slot method update has been registered as a global observer This observer can then be notified in the following manner notifyobservers null In order to provide several independent groups of global observers the optional id operand has to be used The attachobserver statement expects here a uint32 expre
17. These members are always protected hidden The second restriction concerns the definition of multiple variants of a single class constant or resource If two variants do depend on the same variant condition the Embedded Wizard is not able to distinguish between them a Chora compiler error is reported In case of dynamic variants the selection of the appropriate variant depends on the styles activated at the runtime This could cause unexpected behavior at the runtime when two or more variants of a single origin definition do depend on these active styles For this purpose the selection of dynamic variants is always performed regarding to the Z order of the styles only the variant is selected whose Z order is lower The concept of variants is very powerful Beside the derivation of variants from origin classes constants resources and autoobjects it is also possible to derive variants from other variants In this manner complex variant hierarchy can be build Furthermore in the class hierarchy each class can be derived by own variants While the ordinary class hierarchy is only one dimensional the variants extend it by a kind of a second dimension Figure 10 1 demonstrates it Embedded Wizard Copyright TARA Systems GmbH Page 183 Chora User Manual www embedded wizard de Usage of Variants TARA Systems Menu Menu MyMenu Var2 MyMenu Var3 MyMenu MainMenul Custom MainMenu MyMenu MainMenu2 Figure 10 1
18. This means that the resource may contain several versions Each of these versions must be assigned to a particular language One could for example extend the above mentioned Logo resource by a second bitmap for the German language resource Resources Bitmap Logo attr bitmapfile FileName German GermanBanner png Default EnglishBanner png 1 Please note that each language dependent attribute of a resource must always contain a value for the Default language Non language dependent resources are automatically assigned the sole value of the attribute for the language Default Please also note that the names of languages must be defined in the project file In this case the project file must define the two languages German and Default The choice of the suitable language dependent resource occurs automatically at the runtime of the Chora program and is completely transparent to the programmer The programmer needs only to switch between the languages in order to set all resources to the language selected More details in Language selection chapter 9 During translation a resource the Chora compiler makes use of special resource converters Each resource class requires its own resource converter and each Platform Package must contain its own set of such converters This technique guarantees that the definitions of a resource may be ideally transferred to the format of the target platform and that the Chora compiler may
19. native code sequences gt attachobserver detachobserver notifyobservers statements gt These statements provide a powerful observer infrastructure for registration and delivery of notifications between objects It serves as the fundament for the Controller View model In the Controller View model the widgets views and the application logic controllers are always kept apart The observer infrastructure ensures that widgets are notified automatically as soon as the affected controller has changed its state On the other hand user interactions on a widget cause the affected controller to execute the application logic Usually a controller is a simple Chora object containing several properties and the implementation of the onget onset methods 5 1 var declaration statement A var statement is for declaring a local variable The variable can then be used in the method s logic to store intermediate results for example The var statement has these two forms of syntax Form 1 var type expression name Embedded Wizard Copyright TARA Systems GmbH Page 85 Chora User Manual www embedded wizard de Statements TARA Systems Form 2 var type expression name expression The variable s data type is given explicitly with type expression Chora defines a set of data types All of these data types may be used when defining a local variable A detailed description of the data types is found in Data types chapter 6 Optionally
20. object postsignal theSlot Note that in Chora it is not absolutely necessary to react to a signal that is sent If the expression in the postsignal statement results in the value nu11 then no pending signal is recorded and program execution continues without resulting in any runtime errors var slot theSlot null The variable theSlot can still keep null sometimes if visible theSlot theObject OnAction Tey to record the signal postsignal theSlot r The pending signals are delivered strictly in the order in which the corresponding postsignal statements are executed Multiple signals to the same slot will be always merged together and delivered as a single signal If a signal is already pending for the delivery the postsignal statement does not record it twice it moves the recorded signal to the end of the list of pending signals only The example below demonstrates these aspects Record signals to the slots OnActionl OnAction2 and OnActions postsignal theObject OnActionl postsignal theObject OnAction2 postsignal theObject OnAction3 Since OnActionl already waits for the delivery the following statement does not record the signal twice It only changes the order of the signal delivery postsignal theObject OnActionl Embedded Wizard Copyright TARA Systems GmbH Page 98 Chora User Manual www embedded wizard de Statements TARA Systems Due to the last postsi
21. sl find orl O This contains method determines whether the given styles set aStyles is completely enclosed in another styles set If the styles set is enclosed the method returns true Otherwise false is returned var styles a var styles b var bool G Aqua Win95 Win95 oss true c a contains bi This contains method determines whether Page 146 Operators TARA Systems the given set aSet is completely enclosed in arg set type aSet another set If the set is enclosed the method returns true Otherwise false is returned var Unit Align a Unit Align Top Left var Unit Align b Unit Align Left var bool C c true c a contains b Table 7 5 7 9 Instant properties Instant properties simplify access to the instant data types In the case of complex instant data types such as rect point or color instant properties allow direct access to the elements of the data type For example the value of the alpha component in a color data type can be queried or changed using the instant property alpha var color bgColor FFFF0078 var int32 a Query the alpha value of the bgColor a bgColor alpha a 0x78 From the programmer s point of view instant properties are used like the properties of an object with the distinction that instant properties are always used within the context of an instant data type Instant properties are a fixed part of the Cho
22. the resource variant does not specify the resource class nor the meta name of the overridden attributes This information is always inherited from the origin resource Within a resource variant only the values of its attributes can be changed If at the runtime the resource Menu Logo is used Embedded Wizard will automatically use the MyLogo resource variant instead The developer does not need to take care about it Icon Bitmap Menu Logo The Embedded Wizard performs the selection of the resource variant automatically An explicit usage of a resource variant is not allowed The following example will cause a Chora compiler error because MyMenu MyLogo is a variant of the resource and not a real resource Icon Bitmap MyMenu MyLogo Like a real resource a resource variant may store multiple language dependent values for every resource attribute Similarly to the class inheritance a resource variant inherits all values from its ancestor If necessary the inherited values can be modified or new values can be added resource Resources Bitmap Logo attr bitmapfile FileName Default EnglishLogo png German GermanLogo png 7 vresource MyLogo Menu Logo attr FileName Default MyOwnLogo png French FrenchLogo png 1 Embedded Wizard Copyright TARA Systems GmbH Page 77 Chora User Manual www embedded wizard de Unit file EWU TARA Systems In the example ab
23. the variable can be initialized with an expression If the expression is missing the variable is not initialized The Chora compiler will report an error if a non initialized variable is used in an expression The following example demonstrates the use of a local variable tmp to traverse a concatenated list of objects var Core View tmp Views Hide all views while tmp null tmp Visible false Continue with the next view tmp tmp next A variable s validity is limited to the block in which it was defined Within this block the name of the variable must be unique Identically named variables may not be defined within one and the same block For this reason the following code causes a Chora compiler error message if al gt a2 var int32 tmp al 10 if al a2 var int32 tmp The definition of a variable can occur anywhere in the logic of a method where statements are allowed Thus it is possible to define a variable even in the middle of a block Embedded Wizard Copyright TARA Systems GmbH Page 86 Chora User Manual www embedded wizard de Statements TARA Systems var Core View tmp Views var rect union lt 0 0 0 0 gt Show all views and determine the union area occupied by all views while tmp null Show the view tmp Visible true Get the extent of the view var rect extent tmp GetExtent Build a union with
24. until all 5 elements of the array are copied var int32 inx array color list array color list2 Copy all 5 entries of array list1 to the array list2 while inx lt 5 list2 inx listl inx inx inx 1 5 10 return statement A return statement returns control to the calling method The statement can also return a value so that the caller can evaluate it The syntax for the return statement has two forms Form 1 return Form 2 return expression The return statement used without an expression may be used only in a method that can t return values gt The method was defined using the return value type void Using the return statement execution of the method is aborted immediately and the control returns to the caller The return statement used with an expression is used to return the result of the expression to the caller This form of the return statement may only be used ina method that must return a value gt The definition of the method contains a return data type that is not void The Chora compiler reports an error if the return statement used does not match the definition of the method If the method was defined using the return data type void only the first form of the return statement may be used without an expression If the method is to return a value then the method must be closed using the second form of the return statement The following example uses
25. 13 www embedded wizard de Project file EWP TARA Systems affected application Please note the attribute expects that the command has the appropriate file extension specified Tabelle 3 1 Beside the code generation settings the profile may contain one or more macro definitions These definitions must be listed in braces and made subordinate to the profile in the same manner as it is done with the attributes profile Win32 Tara Win32 RGBA8888 macro Debug true macro DefaultFont Verdana In this case the profile was extended by the two macros Debug and DefaultFont Both of these macros are available only if the Chora compiler was launched with the profile Win32 In other profiles the macros are either undefined or they contain other values The profile dependent definition of macros allows the programmer to include profile settings in the definition of classes methods etc Of course the attributes and the macros may be combined together within the profile s definition profile Win32 Tara Win32 RGBA8888 attr Optimization High attr ApplicationClass Example Application attr ScreenSize lt 640 480 gt attr Verbose false attr Clut defaultclut txt macro Debug true macro DefaultFont Verdana Please note that each project must define at least one profile The profile name must be unique Multiple identically named profiles may not be defined in a project file
26. A method is a function of an object In calling a method an object can be made to perform a particular action In the above example the Draw method serves to draw an object on the screen The method s behavior the logic must be defined by the programmer Simply expressed methods are comparable to C functions The unusual thing about methods is that they are always called and executed within the context scope of an object It is therefore not possible to define global methods Optionally the class definition may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Embedded Wizard Copyright TARA Systems GmbH Page 22 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Soutput true class Menu Core Group For more details about the output directive see Control directives chapter 8 3 In Chora it is possible to override a class by so called class variants Class variants provide a powerful technique for the extension and adaptation of classes Each time the class is used Embedded Wizard determines automatically during runtime the appropriate variant and uses it instead gt for more details see Variants chapter 4 8 Within the Embedded Wizard IDE classes appear as bricks in the Unit Composer window A double click on the class brick will show its class members and if th
27. Chora macros can t be placed anywhere within the program code Thus the leading keywords class method enum property var inherited native can t be replaced using macros For example it is not possible to replace the keyword class in the definition of a class by a SCLASS macro SCLASS Menu Core Group Embedded Wizard Copyright TARA Systems GmbH Page 162 Chora User Manual www embedded wizard de Chora preprocessor TARA Systems Even when the macro CLASS would contain the character string class the above example would cause a Chora compiler error because the macro is misplaced In the same way it is not possible to use macros in order to specify the type of a variable or the base class an other class is derived from The following example will also cause a Chora compiler error class Menu MenuSuperClass var MyVariableType Counter Such advanced tricks can be realized much more effectively by using the variants gt see Variants chapter 4 8 For example the class for a menu item can be extended by an additional appearance and behavior depending on the selected profile or style In most cases however macros are used only in the initialization of variables properties and arrays or directly in the logic of methods That already suffices to make the GUI application product and platform independent class Menu Core Group property string Caption Welc
28. Embedded Ke e 34 AAs Ee ee EE 36 EDERT ees becivdsised ee Zeie deeg eegen dias ashatday ouededge texandaged oa sdes Sssapladobet vans Zieser dieggebege genee 54 4 3 Ne te 56 4 3 1 Attributes of a bitmap resource eceeccececeeeeneeceeeeeceaeeeeaaeeeeaeeceaeeesaaeeesaaeedeeeeseaeeesaeeseaeeeeenees 59 4 3 2 Attributes of a font resource ec ceccccceeececeeseeeeeeceeeeeeeseeeeeeseeeeeeeseaseeesseeeeeesscnsaeessensseesssesaeess 61 AA AUC Eil 63 AS INNING el TEEN 65 Rate EE 67 EE 69 4 8 Variants isis 3205s 0c A Sos 5nd bekis cach aa axes aaa dass aad a aia aai Eaa aai aA 71 4 81 Class LEE 72 4 8 2 Constant Variant cccccscccccccscsessesececeeeceeeeseeeeeeececseseeseseeeesecceeseuseseeeeseesseseeseseeeeseeeseseeaeess 74 4 8 3 Resource Vartamts nnn 76 4 8 4 Auto object V ANAM sas sasien a ERE SNE S SEE 79 Ree lun TC 81 IR une teh Bare Gs Bae te ain dads es eee de 82 EE 84 5 1 var declaration statement c cccccseseessesesesesessseseeeseseseseeeseseeeeeeeeeseeeseseeeeeseeeeeseseseseeeseseeees 85 5 2 array declaration statement ertett tt tnnt tt ttnt tn nentrn annt tA nant EA Annn EEEn nE Ennn nE EEEn nE Ennn nn EEEn 87 5 3 Expression NEE 88 54 lee E 89 5 5 Compound statement EE 89 5 6 if selection E EE EE 90 5 7 switch SGISCION statement EE 91 5 8 for iteration StATEMENE cece ccessecececececseseaececeesceceesseaeceecescneseaaeaeceseesceeseaseseceecesseeseaeseeeseess 94 5 9 while iteration st
29. Except for the strictness of the Chora compiler an enumeration can be compared to a C C enum gt Sets gt A set functions in a similar way to an enumeration The only difference to an enumeration is that the elements of a set may be combined in any way This means that a variable of type set may contain any combination of elements of the set including an empty set containing no elements Embedded Wizard Copyright TARA Systems GmbH Page 19 Chora User Manual www embedded wizard de Unit file EWU TARA Systems gt Auto objects gt Objects which are automatically instantiated on request and released as soon as they are not in use anymore Auto objects always exist in the global scope of a unit so they can be accessed from any part of the Chora code Optionally the unit file can be split in several include files one file for each constant resource class etc definition Include files which belong to a unit have to be stored within a directory with the name of this unit While loading a project Embedded Wizard determines whether a unit is stored as a single file or as a directory consisting of several include files The name of an include file has to match the name of the corresponding definition followed by the file extension EWUI For example the definition for the class Core Timer will be stored in the include file Timer ewui within the directory Core ewu Similar to other Embedded Wizard files include files shoul
30. GUI application title as a string literal The SApplicationName macro is replaced by the value of the ApplicationName attribute of the currently selected profile This attribute specifies an optional application name as an identifier e g DashboardApp This attribute allows you to distinguish the application within an environment executing simultaneously multiple Embedded Wizard applications The effect of this attribute depends on the platform package used for the code generation If the generator doesn t support the code obfuscation then the attribute has no effect on the generated code The SScreenSize macro is replaced by the value of the ScreenSize attribute of the currently selected profile This attribute defines the desired size of the screen in pixels as a Chora point literal e g lt 720 576 gt The Clut macro is replaced by the value of the Clut attribute of the currently selected profile This attribute defines the name of the Color Lookup Table CLUT file containing the definition of colors used within this GUI application The CLUT is used for Indexs platforms only Tabelle 8 1 The final limitation concerns the use of reserved preprocessor directives as macros The preprocessor reserves certain keywords which it evaluates as special directives These directives like the macros begin with the character but must not be confused with the macros Thus one may not use the following macros Sif Selse S
31. Generator may perform different code simplification and elimination steps Following levels are available gt None No optimization is performed gt Low Performs only simple optimization steps All invocations of non overridden methods are performed directly without the VMT indirection The read write access to properties is performed without the onget onset method invocations gt Medium Forces the Code Generator to reduce the memory usage of Chora objects the layout of Chora objects is optimized gt High The highest level of optimization forces the Code Embedded Wizard Copyright TARA Systems GmbH Page 11 Chora User Manual www embedded wizard de Project file EWP TARA Systems Obfuscation ScreenSize ApplicationClass ApplicationTitle ApplicationName Embedded Wizard Chora User Manual Generator to eliminate all unreferenced class members variables methods etc The automatic elimination of a class member can be explicitly suppressed by using the Soutput true directive in front of the class member s definition To access the value of the Optimization attribute at the runtime the build in macro Soptimization is available For more details see Optimization chapter 13 The obfuscation attribute controls the format of the generated code If this attribute is true the Code Generator will try to compress and obfuscate the generated code If this attribute is set false the code is not modif
32. It is also not possible to use the same name for a unit and for a profile a language or a style The name of a macro must however be unique only within a particular profile This means that a macro may have the same name as a profile or a unit It is not allowed for two identically named macros to be defined in the same profile Within the Embedded Wizard IDE profiles and macros appear as bricks in the Composer window profile macro Win32_RGBA ii Author A double click on the profile brick will show the macros stored within it The attributes of the profile or the content of the macro can be set directly in the Inspector window when the appropriate profile or macro brick has been previously selected Embedded Wizard Copyright TARA Systems GmbH Page 14 Chora User Manual www embedded wizard de Project file EWP TARA Systems zi profile Win32_Gray profile 11 Win32 RGBA profile 10 P Forms unit g x Brick lt 10 10 150 50 gt Brick lt 10 10 150 50 gt Description Win32 test platform wit Description Clut Content Paul Banach and Manfred Schweyer Optimization None OutputDirectory OutputPrefix PlatformPackage Tara Win32 RGBA8888 ei PostProcess ScreenSize lt 720 576 gt Verbose false Content PlatformPackage The name of the Platform Package assigned to this profile Each profile expects a valid name of the Platform Package the Embedded Wizard x Description S
33. Manual Win32 Splatform is always replaced by the name of the platform package used in the currently selected profile For example Tara Win32 RGBA8888 The Sprototyper macro is replaced by either the value true or the value false depending on whether the code is generated for the target system or for the Embedded Wizard prototyping environment true prototyping environment false target system The composer macro is replaced by either the value true or the value false depending on whether the code is generated for the Embedded Wizard Composer editor or not true composer editor mode false prototyper or target system The verbose macro is replaced by either the value true or the value false depending on the Verbose attribute of the currently selected profile This attribute controls the amount of comments included into the generated code If this attribute is true the Code Generator generates more detailed comments If this attribute is set false only the most important comments are included The effect of this attribute depends on the used Code Generator true verbose mode is on false verbose mode is off The Soptimization macro is replaced by the value None Low Medium or High depending on the value of the Optimization attribute of the currently selected profile This attribute controls the level of optimization during the code generation Depending on the value of this a
34. Manual The Soutput directive accepts also profile names In this case the code generation is forced if the affected profile was selected for the code generation only For example the following method should be generated for the Win32 target system only the name of the profile Win32 appears in the output directive Soutput Win32 void LoadAudioSettings arg bool aMode To build complex conditions the Soutput directive accepts a list of profile names These operands have to be separated by comma signs In this case the output directive is fulfilled if one of the operands is fulfilled For example the following method should be generated for the Win32 or Linux target system only Soutput Win32 Linux void LoadAudioSettings arg bool aMode If the condition in the output directive is not fulfilled the following definition is not generated unless there is a dependency from other parts of the project to this definition In this case the affected definition is automatically involved into the code generation This behavior can t be suppressed If not explicitly specified the default value for this directive is set false for all members For additional details see Optimization chapter 13 The Svariant directive specifies the variant condition for a class constant or resource variant This directive affects only the definition following immediately The simplest version of the variant directive expects a single bool argum
35. TARA Systems GmbH Page 180 Chora User Manual www embedded wizard de Usage of Variants TARA Systems s MenuVariant vclass DemoMenu Menu MenuVariant vclass DemoMenu Menu am Menu class Menu Menu 32 am Menu class Menu Menu 32 Thelcon resource Resources Bitm 31 sl Thelcon resource Resources Bitm 31 Ei Brick lt 560 340 710 380 gt Brick lt 560 340 710 380 gt Description Description MultiLingual false MultiLingual false VariantCond true ell YariantCond true VariantOf DemoMenu Menu VariantOf DemoMenu Menul x VariantCond The variant condition attribute This attribute specifies the condition when the variant should be used in order to substitute the origin class constant or resource ancestor x Variantof The name of the ancestor of this variant This attribute refers to the class constant or resource the variant has been derived from The usage of variants allow an automatic Ei Description Description When working with dynamic variants all desired styles have to be listed previously in the project file This is done using the keyword style style Aqua style WideScreen For more details see Styles chapter 3 4 The styles can be activated and deactivated at the runtime by assigning the desired styles set to the Chora global built in variable styles In the Chora syntax a styles set literal is always enclosed in brackets The following example
36. That is not allowed and causes a Chora compiler error profile Targetl Tara Win32 RGBA8888 macro Size 640 480 macro Rect lt 0 0 Size gt Aside from allowing user defined macros the Chora preprocessor makes its own set of predefined macros available These macros can be used as needed without being defined explicitly in a profile Makro name Description time time is always replaced by a character string consisting of the date and time of the currently running code generation For example 04 02 2003 12 17 59 Sline line is always replaced by the line number of the code in which the line macro is found The numbering of the lines of code is limited only to methods and the inline code definitions and begins each time with the line number 1 For example eons e Spath Spath is always replaced by the full name of the currently evaluated method or inline code definition For example Core Group HandleEvent Core TimerInline version Sversion is always replaced by the version number of the used Chora compiler For example 3 30 Sprofile Sprofile is always replaced by the name of the profile currently selected for the code generation For example Embedded Wizard Copyright TARA Systems GmbH Page 164 Chora User Manual www embedded wizard de Chora preprocessor TARA Systems Splatform Sprototyper Scomposer Sverbose Soptimization Sobfuscation Embedded Wizard Chora User
37. The argument aPrecision defines the number of digits after the point If the aValue number is negative the constructor adds minus sign var string text var float freq 96 5349 text 96 53 text String freq 0 2 This constructor creates a string with the given length aCount and fills the whole string with the copy of the character aChar var string text WkkkaAW text text string 4 This constructor does not expect an argument It returns merely an empty string var string text text text string This constructor initializes a new color with the given values for red green and blue color components and returns the initialized color The alpha component is initialized with 255 var color bgColor var uint8 r 0x12 var uint8 g 0x34 var uint8 b 0x56 bgColor 123456FF bgColor color r g b This constructor initializes a new color with the given values for red green blue and alpha color components and returns the initialized color Page 142 Operators TARA Systems arg uint8 aGreen arg uint8 aBlue arg uint8 aAlpha color color rect rect arg int32 axl arg int32 at arg int32 aX2 arg int32 aY2 rect rect arg point aPointl arg point aPoint2 rect rect point point arg int32 ax arg int32 aY Embedded Wizard Chora User Manual var color bgcolor var uint8 r 0x12 va
38. The following instant data types and their literal notation are supported Data Description type int8 Signed 8 bit integer values in the range 128 127 int16 Signed 16 bit integer values in the range 32768 32767 int32 Signed 32 bit integer values in the range 2147483648 2147483647 uint8 Unsigned 8 bit integer values in the range 0 255 Unsigned integers may be expressed in either decimal or hexadecimal notation A number in hexadecimal notation begins with the prefix 0x var uint8 number 0x12 uint16 Unsigned 16 bit integer values in the range 0 65535 Unsigned integers may be expressed in either decimal or hexadecimal notation A number in hexadecimal notation begins with the prefix 0x var uintl6 number 0x12AC Embedded Wizard Copyright TARA Systems GmbH Page 112 Chora User Manual www embedded wizard de Data types TARA Systems uint32 Unsigned 32 bit integer values in the range 0 4294967295 Unsigned integers may be expressed in either decimal or hexadecimal notation A number in hexadecimal notation begins with the prefix 0x var uint32 number 0x76FF76AB float Floating point number with single precision The actual precision of the float data type can depends on the platform The floating point numbers must always be expressed in decimal point notation var float angle 130 75 bool Boolean data type Defines whether an expression is true or false The boolea
39. To start the idle task an ignition signal should be sent to the task s slot method Afterwards the task s slot method will keep itself running by executing the idlesignal statement The idlesignal statement can be also used if during the initialization of the GUI application some initialization steps may be finalized later but after the screen update is performed To force code execution before the screen update is done the statement postsignal should be used For more details regarding the slot methods see slot methods chapter 4 1 5 4 5 14 throw exception statement A throw statement is used when a fatal non recoverable error has occurred such that continued execution of a program is not possible At runtime the throw statement passes control to an error handler panic function which must undertake all necessary steps to restart the system The throw statement has the following syntax throw expression The expression in the throw statement must result in data type string character string otherwise the Chora compiler will indicate an error This expression should contain a brief description of the cause of the error gt it can for example be displayed on the debug console for debugging purposes The following example demonstrates the use of the throw statement following an invalid object The view has to belong to a group if view group null throw Invalid views owner Embedded Wizard Copyri
40. WideScreen var styles empty The data type styles is used in multivariant GUI applications when at the runtime a variant of a class constant or resource should be determined A multivariant application implements for each style different Embedded Wizard Copyright TARA Systems GmbH Page 115 Chora User Manual www embedded wizard de Data types TARA Systems appearance and behavior This can be switched at the runtime The user can store the styles set within a local variable evaluate the value of this variable use it to switch between variants etc Aside from the data type styles there exists an identically named global built in variable that stores the names of the currently selected styles Details on switching between variants can be found in Usage of Variants chapter 10 slot Slot method data type This data type contains a reference to an object s slot method Through a slot it is possible to send simple signals to an object var slot OnSelect Item Select var slot OnActivate null signal OnSelect Send a signal If a signal is sent to an object s slot the slot method corresponding to the slot is automatically executed The slots and signals provide a simple mechanism for communication between the objects Details on the use of slots are described in slot methods chapter 4 1 5 4 and signal statement chapter 5 11 class Class dat
41. Wizard is completely object oriented and based on the idea of components The components are encapsulated independent building blocks which can be combined with other components to a complex GUI The modeling of components is done with Embedded Wizard IDE ina visual way To implement the functionality of components a large set of Chora statements is available The very big advantage of the Embedded Wizard IDE is the integrated prototyping environment It allows the testing and presenting of the complete GUI application already during the development on the PC without the necessity to download of the application into the target system This document contains the detailed specification of the Chora programming language Usually when you are working with the Embedded Wizard IDE you dont need to know all details of this specification The Embedded Wizard IDE hides the complexity of the GUI application development and makes it much more easy Instead of writing a lot of Chora code you can concentrate on the graphical aspects of your GUI application For more details about the Embedded Wizard IDE see the document Embedded Wizard User Manual Embedded Wizard Copyright TARA Systems GmbH Page 8 Chora User Manual www embedded wizard de Project file EWP TARA Systems 3 Project file EWP Each Chora program must be described by a project file This file specifies what a Chora program consists of and how the Chora compiler should ultimately
42. a var Unit Align b var Uniti Align c Unit Align Top Left Unit Align Left c a b c Unit Align Top Copyright TARA Systems GmbH www embedded wizard de Page 125 Operators TARA Systems P int Pint float float rect point point rect color color color int int color 2int int float float Embedded Wizard Chora User Manual Multiply The result is the product of the both operands var float a 0 1369 var float b 0 1251 var float c C a b c 0 01713 Rectangle inflation The result is the rect operand inflated by moving its sides away from its center by the offset given in the point operand var rect a lt 10 20 30 40 gt var point b lt 5 7 gt Var rect C c a b ce lt 5 13 35 47 gt Alpha blending The result is the left color operand alpha blended with the right color operand The alpha component of the right operand decides about the intensity of the alpha blending If this alpha component is 0 zero the operator returns the left color operand If the alpha component of the right operand is 255 the operator returns the right color operand In all other cases the operator returns a mix color of the both colors var color a FF000080 var color b 00FF0080 var color c c a b ce 7F8000C0 Alpha blending The result is the value of the color operand blended with the value
43. aIndex string string remove Embedded Wizard Chora User Manual Copyright TARA Systems GmbH www embedded wizard de s2 sl left 5 The right method extracts the last that is rightmost aCount characters from the string aString and returns a copy of the extracted substring If acount exceeds the string length then the entire string is returned If acount 0 the method returns an empty string mn var string sl Hello World var string s2 s2 World s2 sl right 5 The middle method extracts a substring of length aCount characters from the string starting at position aIndex within this string The method returns a copy of the extracted substring The argument aIndex contains the index of the first character in the string where the extracted substring begins The characters in a string are counted from 0 zero If acount 0 the method returns an empty string mn var string sl Hello World var string s2 s2 llo s2 sl middle 2 3 The insert method inserts the substring aString at the given position aIndex within the string If aIndex is lt 0 zero the insertion will occur before the entire string If aIndex is greater than the length of the string the function will concatenate aString at the end of the string var string sl Hello World var string s2 s2 Hello nice World s2 sl insert nice 6 The remove method
44. aValue As this example indicates the Power2 method returns an int32 82 bit signed integer value In the logic of the method the argument aValue is used to calculate the power value and this result is returned The caller of the Power2 method can then use this result directly in an expression var Sample Math math new Sample Math var int32 X 10 var int32 y 32 var int32 result result x y result math Power2 x math Power2 y Through class derivation all methods defined in the base class are automatically inherited by the new class The inherited methods do not have to be redefined unless the programmer wishes to change the behavior of the inherited method Then and only then the definition of the inherited method may be declared again and assigned a different logic Embedded Wizard Copyright TARA Systems GmbH Page 38 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class SubMenu Sample Menu inherited method HandleFocus If the menu loses the focus hide this menu if aObtain false Hide Let the super class a chance to respond to the focus change super aObtain Note the use of the keyword inherited Each inherited method that is to be used anew in the derived class must be introduced using the keyword inherited If this keyword is missing the Chora compiler will report an error message Moreover the return
45. an expression must be subjected to an explicit conversion of its data type Such a type conversion can be necessary when the data type of the operand can t be used directly in the expression or when ambiguities exist in the possible evaluation of the expression When an instant cast operator is used the desired target data type must be given in parentheses in front of the operand var float f 1 1369 var int32 i 4 var float fr var int32 ir fr f float i fr 5 1369 LE int32 f i ix Wu Embedded Wizard Copyright TARA Systems GmbH Page 133 Chora User Manual www embedded wizard de Operators TARA Systems The addition of a float and an int32 operand shown in the above example would not be possible without an instant cast operator In contrast to C C the Chora programming language does not allow the addition of two operands of data type float and int32 In such a situation the Chora compiler can t conclusively recognize which results should arise from the expression float or int32 This conflict can be resolved easily by subjecting one of the two operands to an explicit type conversion in such a way that the result reflects the programmer s intention If the programmer expects that the addition yields a float value then the int32 operand in the expression must be converted into float If on the other hand it is expected that the expression yields an int32 value then the float operand mus
46. and the variant depends on the style Aqua then two different objects of the same class can be created at the runtime Embedded Wizard Copyright TARA Systems GmbH Page 182 Chora User Manual www embedded wizard de Usage of Variants TARA Systems var Menu Menultem objectl var Menu Menultem object2 Ensure the styles are deactivated and create the object styles objectl new Menu MenulItem Activate the style and create an object of the variant styles Aqua object2 new Menu MenulItem After the creation the both objects retain their derivation hierarchy until the objects are disposed Anyway because the objects are instantiated from different class variants they may and will behave differently In these class variants new members could be added and the logic of inherited methods could be overridden Anyway these objects can coexist simultaneously and the Embedded Wizard can handle them properly This is a special feature of Chora The one restriction in the usage of variants is that the variants itself can never be accessed directly within an expression This is because the variants are not handled as independent definitions they always belong to the origin definition If possible the variants are combined together with their ancestors or they are completely eliminated In the case of a class variant it is not possible to access its new added members from the outside of the variant
47. attribute refers to the class constant or resource the variant has been derived from The usage of variants allow an automatic His Description 4 8 2 Constant Variants Constant variants are always introduced by the keyword vconst followed by the name of the variant and the name of the origin constant its ancestor vconst MyCaption Menu Caption Video Settings Using this definition we have created a variant MyCaption of a constant Menu Caption The variant inherits all language dependent values from the origin constant and overrides the default value with the string Video Settings Please note the constant variant does not specify the data type of its content This data type is always inherited from the origin constant Within a constant variant only the values of the constant can be changed If at the runtime the constant Menu Caption is used Embedded Wizard will automatically use the MyCaption constant variant instead The developer does not need to take care about it Dialog Caption Menu Caption Embedded Wizard Copyright TARA Systems GmbH Page 74 Chora User Manual www embedded wizard de Unit file EWU TARA Systems The Embedded Wizard performs the selection of the constant variant automatically An explicit usage of a constant variant is not allowed The following example will cause a Chora compiler error because MyMenu MyCaption is a variant of the constant and not a real constant Dialog C
48. both rect operands If the union area is empty the operator returns an empty rectangle var rect a lt 10 5 110 220 gt var rect b lt 10 50 50 75 gt var rect c c a b ce lt 10 50 110 220 gt If one of the operands is an empty rectangle no union is build and the operator returns the other operand immediately var rect a lt 10 5 110 220 gt var rect b lt 0 0 0 0 gt var rect c c a b c lt 10 5 110 220 gt Bitwise vor exclusive orl The result is the bitwise xor of both operands OxFFOO3ACO0 OxABI5FEF70 var uint32 a var uint32 b Copyright TARA Systems GmbH www embedded wizard de Page 128 Operators TARA Systems var uint32 c c a b c 0x5415C5B0 styles styles Exclusive or of two styles sets The result is a new styles set which contains the style names enclosed exclusively either in the left or in the right operand but not in both var styles a Aqua Win95 var styles b Win95 Blue var styles c c a b c Aqua Blue S set set Exclusive or of two sets The result is a new set which contains the enumerators enclosed exclusively either in the left or in the right operand but not in both var Unit Align a Unit Align Top Left var Unit Align b Unit Align Top var Unit Align c c a amp amp b c Unit Align Left amp amp rect amp amp rect Rectangle intersection The result
49. converter takes over this default character automatically it is not necessary to specify it explicitly in the Ranges attribute Embedded Wizard Chora User Manual Copyright TARA Systems GmbH Page 62 www embedded wizard de Unit file EWU TARA Systems Additionally please note that Embedded Wizard handles multilingual font resources in a different way as it is habitual to do with e g bitmap resources Instead of selecting an appropriate language variant of a font resource Embedded Wizard combines the several language variants together and considers them as a single large virtual font In this manner the programmer can create complex fonts which can be used to display text consisting of absolutely different character sets all at once For example the programmer can create a font resource which combines the Latin character set from the Arial 18 font the Greek character set from the Verdana 16 font and some Japanese signs from the Arial Unicode 16 font This font resource can then be used to display text for all the supported languages independently of the currently selected language Within the Embedded Wizard IDE the font resources appear as bricks in the Unit Composer window The attributes of the resource can be set directly in the Inspector window when the appropriate resource s brick has been previously selected F MenuFont resource Resources F Menu class Forms Form 2 Menultem class Forms Ct
50. data type and the arguments list in the derived class may not be specified Only the first definition of the method expects the return data type and optionally the arguments list Inherited methods will inherit the return data type and the arguments list from theirs ancestors The implementation of the methods changed in the derivation is valid only for objects of this derived class Objects of one of the base classes are not affected by the change and their methods retain the originally defined logic The derivation and overriding of methods form one of Chora s most important concepts It is a simple matter for the programmer to extend the behavior of a derived class without having to change the definition of this class He needs only to override all the methods that are affected by the change All other methods that are not explicitly overridden are automatically inherited by the derived class Please note that the inheriting of methods does not at all mean that there will be more than one copy of one and the same method at runtime As long as a method has only been inherited and not overridden the base class and the inherited classes share this single implementation of the method Overriding a method allows the programmer to change a method s behavior completely If such an overridden method is called at runtime the logic of this method is run The method originally defined in the base class is no longer executed the base version
51. data type from theirs ancestors A property s initialization value changed during derivation is valid only for objects of the derived class Objects of one of the base classes are not affected by the change and their properties retain their original initialization values var Sample Item objectl new Sample Item var Sample SoundItem object2 new Sample SoundItem In this example the first object an object of class Sample Item still has the original initialization value for Caption namely Video Settings The second object on the other hand has been initialized by the derived class Sample SoundItem In this case the object s Caption property will be given the value Sound Settings Unlike with variables a property s initialization process requires additional explanation in order for one to understand the underlying mechanisms If a property is initialized first time without an inherited keyword the initialization value used in the definition of the property is copied directly into the property s memory There is no call to the onset method This is exactly the same as when a simple variable is initialized class Item Copy the string Video Settings to the memory area of the property like pure keyword property string Caption Video Settings If on the other hand a property that has already been defined in the base class is re initialized in the derived class then the onset met
52. definition of a constructor is similar to an ordinary method A constructor always has the name Init expects none or exactly one argument of data type uint32 unsigned 32 bit integer and may not return a value class Timer method native void Init Sif Splatform Tara Win32 Allocate an OS timer etc StartTimer Sendif Note the constructor may declare a single uint32 argument This optional argument is for internal purpose only Usually the user defined constructors should never use this optional argument class Timer method native void Init arg uint32 aArg Sif Splatform Tara Win32 Allocate an OS timer etc StartTimer Sendif The constructors are automatically called by the Chora Runtime Environment when an object is created to give the object the chance to request additional resources etc It is not necessary and in fact unadvisable to call the constructors directly from the Chora code This can lead to inexplicable runtime errors Embedded Wizard Copyright TARA Systems GmbH Page 50 Chora User Manual www embedded wizard de Unit file EWU TARA Systems var Core Timer timer new Core Timer DON T call constructors directly timer Init 0 Because constructors are optional the absence of constructors does not lead to an error message they are simply ignored The Chora compiler recognizes whether a class has defined a constructor
53. error message Moreover the data type and size of the array may not be redefined in the derived class Only the first definition of the array expects the data type Inherited arrays will inherit the data type and the size from theirs ancestor The initialization values for an array that are changed during derivation are valid only for objects of the derived class Objects of one of the base classes are not affected by the change and their arrays retain the original initialization values var Sample Menu objectl new Sample Menu var Sample SubMenu object2 new Sample SubMenu In this example the first object an object of class Sample Menu still contains the original initialization values for Captions namely Video Settings and Sound Settings The second object on the other hand was instantiated by the derived class Sample SubMenu In this case the object s Captions array will contain the two values Brightness and Contrast Additionally it is possible to define an array consisting of more than one dimensions For this purpose the sizes of all dimensions have to be placed between the braces and separated by commas class Menu array int32 Field 4 5 Default 0 0 1 Default 0 1 2 20 Default 3 4 1 The access to an multi dimensional array works in the same way as the access toa single dimensional array The index of the required array element consists of more expressions separated by comma
54. example the timer object must be dismissed shortly before its destruction by the operating system in order not to receive any more timer events In this case the timer object s destructor handles the required deregistration from the operating system Relnit re constructors gt Re constructors are special methods that are automatically invoked in order to complete the re initialization of an object The re initialization is triggered by the language selection Each time a preferred language is selected by the user the Chora Runtime Environment forces all existing objects to adapt themselves to this new language In this manner language dependent constants and resources are reloaded into the objects and the GUI application appears in the newly selected language on the screen automatically In rare cases it may however be necessary for an object to execute additional code during its re initialization This can be done in this Relnit method Note unlike the Init constructor the re constructor is called multiple times during the lifetime of an object Optionally the method definitions may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Embedded Wizard Copyright TARA Systems GmbH Page 40 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Soutput true method void LoadAudioSetting bool
55. for the generated file names The value of this attribute is only a suggestion for the Code Generator how the generated files should be named If the Platform Package is not able to evaluate this attribute the prefix will be ignored This attribute was intended in order to support the customer specific build processes Please note the usage of this attribute influences the interface to the generated code whereby compilation errors might occur The user defined command which will be executed at the end of the build process The command can be an EXE BAT or a CMD file and it can be followed by any arguments e g the command to start the make job after the code generation is finished nmake exe f makefile mak This attribute is optional If specified Embedded Wizard searches for the command file starts it in a new process and waits for its termination Any outputs of the command will be stored in a log file in the destination directory of the current profile The working directory of the command is per default set to the current project directory If the command is specified without a path or the specified path is relative Embedded Wizard first searches for the command file in the current project directory and then in the Embedded Wizard installation directory In case of an EXE file the Windows directory and the directories specified in the PATH environment variable are evaluated in order to find the Copyright TARA Systems GmbH Page
56. if the operand is false var bool a true var bool c c l a c false Table 7 1 7 2 Binary instant operators A binary instant operator expects exactly two operands For example the string concatenation operator can be used in an expression to join two character strings into one long string var string Stringl Hello var string String2 world var string Result Result Stringl Stringz In this example the two strings Stringl and String2 separated by a space are joined and assigned to the variable Result The result is Hello world Chora supports the following binary operators Operator Operand Description name data types sata t o Addition The result is the arithmetic sum of the oat float operands var int32 a 1369 var int32 b 1251 var int32 c c a b c 2620 string Tn String concatenation The result is a string o Kees containing a copy of the left operand followed by the copy of the right operand var string a Hello var string b World var string c n c a b c Hello World rect point Rectangle movement The result is the reci point rect operand moved by the offset given in the poini operand The movement will be done in the positive direction T T Embedded Wizard Copyright TARA Systems GmbH Page 123 Chora User Manual www embedded wizard de Operators TARA Systems point po
57. int32 aValue result arg int32 aNoOfDigits The constructor adds leading zeros 0 until the resulted string has reached the length given in the aNoOfDigits argument If the number is negative the constructor adds minus sign var string text var int32 pegel 12 text 0012 text string pegel 5 string string This instant constructor converts the given unsigned number aValue in a string and arg uint32 avalue returns the result arg int32 aNoOfDigits a The constructor adds leading zeros 0 until the resulted string has reached the length given in the aNoOfDigits argument var string text var uint32 volume 55 text 055 Embedded Wizard Copyright TARA Systems GmbH Page 141 Chora User Manual www embedded wizard de Operators TARA Systems string string arg float avValue arg int32 aNoOfDigits arg int32 aPrecision string string arg char aChar arg int32 aCount string string color color uint8 aRed uint8 aGreen uint8 aBlue arg arg arg color color arg uint8 aRed Embedded Wizard Chora User Manual Copyright TARA Systems GmbH www embedded wizard de text string volume 3 This constructor converts the given floating point number aValue in a string and returns the result The constructor adds leading zeros 0 until the resulted string has reached the length given in the aNoOfDigits argument
58. is a rectangle that represents the intersecting area of the both rect operands If the intersecting area is empty the operator returns an empty rectangle Unlike the rectangle intersection operator amp empty rectangles are ignored If one of the operands is an empty rectangle no intersection is build and the operator returns the other operand immediately var rect a lt 10 5 110 220 gt var rect b lt 0 0 0 0 gt var rect Cy c a amp amp b c lt 10 5 110 220 gt amp amp bool amp amp bool Logical and The result is true if both operands are true var bool a true var bool b true var bool c c a amp amp b c true bool bool Logical or The result is true if one of the operands is true var bool a true Embedded Wizard Copyright TARA Systems GmbH Page 129 Chora User Manual www embedded wizard de Operators TARA Systems var bool b false var bool c c a b c true rect point Ig point in rectangle test The result of this point rect expression is true if the given point does lie within the area of the rect operand lt 0 0 100 200 gt lt 10 20 gt lt 200 300 gt var rect var point var point var bool cr CT DO D o I e d d b d true a a c d false CES Op1 Op2 Equal to The result of oi Op2 is true if both any datype operands are identical This operator can be used for all data types The data t
59. is an instance of its class gt parentthis operator gt The parentthis operator determines the parent object of this object The operator works for embedded objects only and allows these objects to determine their parent If an object has not been embedded within another object parentthis results in null gt classof operator gt The classof operator determines the class of a given object at the runtime gt Instant constructors gt An instant constructor allows the dynamic creation construction of instant data types at runtime of a Chora program The instant constructor works in a way similar to a C or Java constructor except that the instant constructor returns not an object but an instant data type For each instant data type Chora defines a set of instant constructors Thus the programmer can for example construct a rectangle from two points by using the instant constructor rect with two point arguments rect p1 p2 gt Instant methods gt Instant methods simplify access to the instant data types The programmer can use the instant methods to execute an operation on an instant data type He can for example search a string for a particular character using the instant method find From the programmer s point of view instant methods are used like the methods of an object gt Instant properties gt Instant properties simplify access to the instant data types In the case of complex instant data types such aS r
60. method The hidden argument sender is always nu11 if the slot method is invoked due to a pending signal For more details see signal statement chapter 5 11 Unlike the postsignal statement the delivery of idle signals is performed always after the screen update is done and no user inputs wait for the execution For more details see postsignal statement chapter 5 12 Please note that pending signals do affect the garbage collection As long as an object is waiting for a signal the object is still reachable and will not be reclaimed by the Garbage Collector For more details see Garbage collection chapter 11 Embedded Wizard Copyright TARA Systems GmbH Page 100 Chora User Manual www embedded wizard de Statements TARA Systems Idle signals are very useful to perform idle background tasks An idle task should always be executed in several small steps In this manner the GUI application can continue responding to the user inputs while the idle task performs its job step by step in the background For example the time consuming decoding of a JPG picture can be done by an idle task in several steps Each time an idle signal is delivered the next decoding step is executed slot MyIdleTask Perform the next decoding step Decode Anything more to do next time If yes request one more idle signal if AnythingMoreToDo idlesignal MyIdleTask otherwise the task is done else
61. most cases however minor adjustments must be made to the GUI application in order to fit the resolution and color depth of the new target system The logic of the native methods native statements and the inline code definitions must also be adjusted accordingly In order to simplify all the necessary changes and adjustments within the GUI application the Chora programming language contains a preprocessor This preprocessor analyses the source code of the GUI application and enables conditional code generation that depends on the chosen platform profile or other user defined settings gt The preprocessor s first job is to evaluate and replace macros The programmer uses macros in order to store arbitrary character strings under a unique name If the preprocessor finds such a macro name in the GUI application it will automatically replace that name with the relevant character string With the aid of a macro the screen resolution for example can be set platform independently Wherever the GUI application has to query the screen resolution the macro can be used gt The code of the GUI application thus remains platform independent See Profiles and macros chapter 3 2 gt The second job for the preprocessor is the conditional code generation through the evaluation of the if else elseif and endif directives With the aid of these directives some code lines of a method or an inline code definition can be excluded from the code gen
62. of the integer operand This operator applies the alpha blending algorithm on all 4 color components red green blue alpha of the given color var color a FFOOOOFF var int32 b 0x80 var color c c a b c 80000080 Division The result is the quotient var float a 0 1369 var float b 0 1251 var float c Copyright TARA Systems GmbH www embedded wizard de Page 126 Operators TARA Systems 2int int gt gt P int gt gt Pint lt lt P int lt lt Pint amp Pint amp Pint amp rect amp rect amp styles amp styles Embedded Wizard Chora User Manual c a b c 1 0943 Remainder modulo division The result of the operation is the reminder var int32 a 34 var int32 b 8 var int32 c os a S b c 2 Shift right The result is the value of the left operand right shifted by right operand bit positions zero filled from the left if the left operand is unsigned operand If the left operand is of signed type int8 int16 int32 the fill from the left uses the sign bit 0 for positive and 1 for negative var uint32 a 0x00AA5500 var uint32 b 1 var uint32 c c a gt gt b c 0x552A80 Shift left The result is the value of the left operand left shifted by right operand bit positions zero filled from the right if necessary var uint32 a O0x00AA5500 var uint32 b 1 var uint32 c c a lt lt b
63. previously selected Embedded Wizard Copyright TARA Systems GmbH Page 64 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Timer autoobject Core Timer 27 55 Enum enum 26 e Inline inline 25 MenuCaption const string 24 Brick lt 10 100 150 140 gt Class Core Timer Description Generator false Begin 0 Enabled false v OnTrigger null Period 1000 Enabled The property Enabled defines whether the timer can trigger timer events or not If D Description E 4 5 Inline code An inline definition must always be introduced using the keyword inline followed by the name of the definition and a user defined code block inline Includes include lt rtos api h gt include lt stdio h gt Here a code block is defined containing two ANSI C include directives This code block is automatically inserted into the generated ANSI C file without any changes The use of inline definitions allows a mixture of Chora and native code However it prevents platform independent GUI development In practice inline definitions should be used only in developing driver classes A driver class serves as an interface between the GUI and the underlying target system By adapting the driver class the GUI program can be ported to other target platforms In order to differentiate between different target platforms within an inline definition it is necessary to use the Chora preprocessor d
64. removes up to aCount Page 145 Operators TARA Systems int32 int32 aIndex aCount arg arg int32 string find arg char aChar arg int32 aStartIndex int32 string find arg string aString arg int32 aStartIndex bool styles contains arg styles aStyles bool set contains Embedded Wizard Chora User Manual Copyright TARA Systems GmbH www embedded wizard de characters from the string starting with the character at position aIndex and returns a copy of the resulted string var string sl Hello World var string s2 s2 Hello s2 sl remove 5 6 This find method searches the string for the first occurrence of a character aChar find starts the search operation at the position aStart Index in the string The function returns the index of the first character in the string that matches the requested character aChar or 1 if achar has not been found in the string var string sl Hello World var int32 inx inx 7 gt second Toi inx sl find Toi 5 This second find method searches the string for the first occurrence of a substring aString find starts the search operation at the position aStart Index in the string The function returns the index of the first character in the string that matches the requested substring aString or 1 if aString has not been found in the string var string sl Hello World var int32 inx Ans 7 inx
65. string Sound Settings Please note that the elements of an array are always counted from 0 The first element is number 0 the second 1 and so on The values of an array that have not explicitly been given an initialization value are given a default value of O zero A non explicitly initialized string array if the initialization for Captions is missing would thus contain only empty strings Please note that the name Default must always be given at initialization and that the name does not have anything to do with the default value 0 zero It is not absolutely necessary for all elements of an array to be dealt with at initialization It is possible to explicitly initialize only selected elements of an array while the other values are preassigned the default 0 zero value class Menu array int32 Counters 8 Default 0 Default 3 1 1251 1369 As the above example demonstrates only the first and fourth element of the array have been initialized All other elements of the array still contain the value 0 zero Chora defines a set of data types All of these data types may be used in the definition of an array A detailed description of data types can be found in Data types chapter 6 Access to an array always occurs in the context of the object to which the array belongs var Sample Menu theObject new Sample Menu theObject Captions 0 Brightness theObject Captions 1 Contrast Be
66. string point rect color etc operators into expressions var rect Bounds lt 0 0 200 100 gt var rect Clipping lt 10 10 20 20 gt var rect Result Result Bounds lt 5 2 gt amp Clipping This example demonstrates how the rectangle named Bounds is moved a distance of lt 5 2 gt pixels and then forms an intersection with a second rectangle Clipping The result of this operation is assigned to the rectangle Result The clarity and simplicity with which the programmer can form complex operations using few operators are the strengths of Chora The operators are fundamentally divided into the following categories gt Instant operators gt These are operators in the classical sense such as amp lt The programmer can compute using these operators regardless of whether he is working with numbers colors rectangles and so on Each instant data type supports its own set of operators that are adapted to it Depending on the number of operands expected the instant operators are divided into two categories gt Unary instant operators gt These operators work with only one operand gt Binary instant operators gt A binary operator expects 2 operands gt Instant cast operators gt These operators enable different instant data types to be explicitly converted Thus the programmer can convert for example a floating point number float to an integer int32 Not all type conversions
67. the Embedded Wizard only During the code generation the statement is replaced by an empty statement 5 17 native statement The native statement inserts a user defined native code block into the body of the method The syntax for the native statement has two forms Form 1 native native code block Embedded Wizard Copyright TARA Systems GmbH Page 102 Chora User Manual www embedded wizard de Statements TARA Systems Form 2 native identifier identifier native code block The native statement allows the mixing of the platform independent Chora code with the target specific code During the code generation the native code block is taken over without any modifications into the body of the generated method The native code block is always enclosed by two braces For example the following method contains the Chora code and a native statement with two target specific C function calls At first use Chora to create a new object var Menu Item item new Menu Item H tem Caption Volume tem OnAction OnAction H Now force some C function calls which are strict target specific native dispatch_command CMD_UPDATE_TUNER send _i2c_command Einally display the previously created menu item This can and should be expressed in the platform independent Chora language Add item O0 The Chora compiler ensures that all Ch
68. the if selection statement to test the validity of the variable Size Assuming the variable may contain only values in the range 0 100 the if selection statements serve to correct the value of Size var int32 Size if Size gt 100 Size 100 else if Size lt 0 Size 0 When nesting if statements and else clauses use braces to group the statements and clauses into compound statements that clarify your intent If no braces are present the Chora compiler resolves ambiguities by associating each else with the closest if that lacks an else 5 7 switch selection statement The switch statement transfers control to one of several statements depending on the value of the expression The syntax for the switch statement has the following form switch expression case statement list case statement list default statement case statement case statement list case statement case statement case expression list statement A switch statement consists of one expression any number of case statements and an optional default statement These statements help control complex conditional and branching operations which would otherwise only be possible through the use of nested if else statements The following example demonstrates the use of the switch statement in evaluating user input Embedded Wizard Copyright TARA Systems GmbH Page 91 Chora User Manual www embedded wizard de Statements TARA Systems var Core K
69. the return statement to prematurely stop execution of the method if value has not changed Embedded Wizard Copyright TARA Systems GmbH Page 96 Chora User Manual www embedded wizard de Statements TARA Systems Nothing to do If no gt return immediately if value oldValue return oldValue value 5 11 signal statement A signal statement sends a signal to an object in order to notify that object of an event The signal is sent to a slot of an object using the corresponding slot method The signal statement has the following syntax Signal expression The expression in the signal statement must result in data type slot otherwise the Chora compiler will indicate an error The following example demonstrates the use of the signal statement to send a signal to the OnAction slot of the object theObject var slot theSlot theObject OnAction send a signal to the OnAction slot of the theObject object Signal theSlot Note that in Chora it is not absolutely necessary to react to a signal that is sent If the expression in the signal statement results in the value nu11 then no signal is sent and program execution continues without resulting in any runtime errors var slot theSlot null The variable theSlot can still keep null sometimes if visible theSlot theObject OnAction Try to send the signal Signal theSlot When a signal is sent the identity of the sender object is passed o
70. var point c Get the bottom right edge c a point2 c lt 30 50 gt Move the bottom right edge a point2 lt 35 57 gt a lt 10 20 35 57 gt The instant property origin corresponds to the origin of the rectangle The read access to this property returns the coordinates of this origin edge and the write access moves the whole rectangle so the size of the rectangle doesn t change This behavior is the most important difference to the pointl instant property which changes the coordinates of the top left edge only var rect a lt 10 20 30 50 gt var point c Get the origin edge c a origin c lt 10 20 gt Move the whole rectangle a origin lt 5 7 gt a lt 5 7 25 37 gt Copyright TARA Systems GmbH Page 152 www embedded wizard de Operators TARA Systems point rect size rect rect orect int32 rect area point rect center Embedded Wizard Chora User Manual The instant property size corresponds to the size of the rectangle The read access to this property returns the size width height and the write access changes it The origin of the rectangle still keep unchanged The size of the rectangle is calculated by subtracting the coordinates of the top left edge X1 Y1 from the bottom right edge X2 Y2 var rect a lt 10 20 30 50 gt var point c Get the size of the rectangle c a size c lt 20 30 gt Resize the rectangle a size lt 10 1
71. www embedded wizard de Unit file EWU TARA Systems class Menu Core Group object Sample Item Item This is a misplaced comment line because the preset can t be commented preset Caption Sound Settings A comment must always directly precede the definition to which it applies Comments are very useful to document the functionality of classes methods properties etc Embedded Wizard uses the content of comments to give you a short description of members which have been selected in the Composer window of the Embedded Wizard application This description appears below the Inspector window For more details see Embedded Wizard User Manual Additionally Embedded Wizard is able to generate a documentation file with the description of your project including the class hierarchy declaration of classes methods properties constants resources etc This automatic generated documentation file can then be used or distributed as software reference manual of your project Further details to comments and their syntax can be found in Comments chapter 12 4 10 Example The following example shall demonstrate the structure of a very simple unit file The unit consists of a bitmap resource and a class At runtime an object of this class will be able to output the contents of the bitmap resource on the screen This example is based on the Mosaic class library Embedded Wizard Copyright TARA System
72. 10 20 30 50 gt var int32 c Get the width c a w c 20 change the width a w 1007 a lt 10 20 110 50 gt int32 rect h The instant property h corresponds to the height of the rectangle The read access to this property returns the height and the write access changes it The height of the rectangle is calculated by subtracting the coordinates of the top border Y1 from the bottom border Y2 var rect a lt 10 20 30 50 gt var int32 c Get the height c a h c 30 change the height a h 100 a lt 10 20 30 120 gt Embedded Wizard Copyright TARA Systems GmbH Page 151 Chora User Manual www embedded wizard de Operators TARA Systems point rect pointl point rect point2 point rect origin Embedded Wizard Chora User Manual The instant property point1 corresponds to the top left edge of the rectangle The read access to this property returns the coordinates of this edge and the write access changes them The other edge is not affected var rect a lt 10 20 30 50 gt var point c Get the top left edge c a pointl c lt 10 20 gt Move the top left edge a pointl lt 5 7 gt a lt 5 7 30 50 gt The instant property point2 corresponds to the bottom right edge of the rectangle The read access to this property returns the coordinates of this edge and the write access changes them The other edge is not affected var rect a lt 10 20 30 50 gt
73. 11 if the tested class is not derived from the desired class var class theClass classof anObject if Core Group theClass null Yes it is derived from Core Group For more details see new operator chapter 7 6 and the description of the class type in Instant data types chapter 6 1 7 14 Build in functions Besides the instant operators and methods Chora also provides some build in functions useful for common mathematical calculations Following functions are available Embedded Wizard Copyright TARA Systems GmbH Page 159 Chora User Manual www embedded wizard de Operators TARA Systems float math_sin float aAngle float math_cos float aAngle float math_asin float aValue float math_acos float aValue float math_pow float aA float aB float math_sqrt float aValue float math_rand float aValuel float aValue2 int32 math_rand int32 aValuel int32 aValue2 The trigonometric functions math_sin and math_cos calculate the sine and cosine values of the given angle aAngle expressed in degrees For example var float angle 60 0 var float x math_cos angle x 0 5 var float y math _sin angle y 0 86602 The inverse trigonometric functions math _asin andmath_acos calculate the arcsine and arccosine of the given value aValue The functions return the angle in degree For example var float a
74. 5 gt a lt 10 20 20 35 gt The read access to the instant property orect of a rectangle returns a copy of this rectangle moved to the zero origin lt 0 0 gt The size of the rectangle doesn t change var rect a lt 10 20 30 50 gt var rect c c a orect c lt 0 0 20 30 gt This instant property is read only You can t assign any values to orect The instant property area can be used to determine the area occupied by the rectangle The area is calculated by multiplying the width and the height of the rectangle If the width or the height are negative the resulted area can be negative too If the width or the height are zero an empty area results var rect a lt 10 20 30 50 gt var int32 c c a area c 600 This instant property is read only You can t assign any values to area The instant property center calculates the coordinates of the point in center of the rectangle var rect a lt 10 20 30 50 gt var point c Copyright TARA Systems GmbH Page 153 www embedded wizard de Operators TARA Systems c a center c lt 20 35 gt This instant property is read only You can t assign any values to center bool rect isempty The instant property isempty is used to determine whether a rectangle is empty or not An empty rectangle has an area equal to or less than zero x1 gt x20ryl gt y2 AN var rect a lt 10 20 30 50 gt var rect b lt 10 20 10 50 gt
75. 9 or decimal notation e g 48 58 The Ranges attribute allows the programmer to specify more than one character range for a single font resource In this case the ranges are separated by the comma sign e g A Z a z O 9 x0020 All these characters will be then affected by the font conversion In this manner different character ranges for different languages can be included into a single font resource Additionally it is possible to map a single range of characters to another character code For this purpose the desired destination character is specified after the colon sign e g a z A forces the font converter to convert the lower case characters and to map them to the range of the upper case characters This mapping is optionally and it can be applied to each range separately Alternatively the attribute can specify a path referring to a text file containing the desired font character ranges e g file txt The syntax of this file should correspond to the syntax described above If the file name contains a relative path the file will be looked for relative to the directory of the unit file where the font resource is defined Table 4 2 Note The converted font resource includes additionally the default character This character will be displayed on the screen instead of the characters which are not contained in the font resource The code of the default character is specified in the TrueType font The font
76. Another value etc Additionally an onget method can like any other method contain native code Embedded Wizard Copyright TARA Systems GmbH Page 44 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class Time property int32 Seconds 0 onget native Seconds if platform Tara Win32 return clock Sendif Further details on properties are found in Properties chapter 4 1 3 and Reference data types chapter 6 3 4 1 5 3 onset methods onset Methods are always introduced with the keyword onset followed by the data type of the corresponding property the properties name and the logic the body of the method class Menu property color Color 000000FF onset Color Store the new value in the memory pure Color value In the above example the Menu class has been given a property named Color and a corresponding onset method Note that the name of the property must correspond exactly to the definition of the onset method If this is not the case the Chora compiler will report an error message Unlike other methods onset doesn t expect the return data type nor the arguments list The Chora compiler will adopt the data type of the property for the hidden value argument of the corresponding onset method automatically Each time that the value of the Color property is to be changed in an expression the property s onset method is called automati
77. As expected this operation causes the Chora Runtime Environment to deliver a signal to the previously registered slot method update In the case there have been several methods attached to the triggered property all affected slot methods will receive the signals The attachobserver statement does not really connect the slot method with the given property It uses the property as a unique ID only This ensures that different observer groups may exist at the same time without any conflicts The following example demonstrates it First attach two observers to two different properties attachobserver updateThis firstController VolumeLevel attachobserver updateThat secondController VolumeLevel Then notify the observers attached to the property secondController VolumeLevel In response to this the slot method updateThat will receive a signal wodateThis will not notifyobservers secondController VolumeLevel If the observer is no more needed the statement detachobserver can be used After the following operation the slot method update is detached from the property it is not able to receive any notifications triggered for the VolumeLevel property detachobserver update controller VolumeLevel For more details about detachobserver see detachobserver statement chaper 5 19 Embedded Wizard Copyright TARA Systems GmbH Page 106 Chora User Manual www embedded wizard de
78. Caption This example demonstrates the initialization of two variables with the value of the constant Caption defined within the unit named Sample Each time a constant is used in the Chora program the name of the unit in which the constant has been defined must also be given This ensures that the Chora compiler knows where to find the definition of the constants Further it prevents constant definitions with the same name in different units from causing name conflicts Following translation with the Chora compiler the value of a constant may no longer be changed An attempt to assign another value to a constant after the fact is not possible and results in an error message from the Chora compiler Sample Caption Sound Settings A constant always contains a value that fits the constant s data type The possible data types are integrated into the Chora programming language These data types allow the programmer to define constants with numbers colors and even rectangles as values For more details see Data types chapter 6 A constant may be language dependent This means that the constant can contain more than one value Each of these values must be assigned to a particular language The Caption constant shown above could for example be extended to include a second value for the German language const string Caption German Bildeinstellungen Default Video Settings 1 Please note that every languag
79. Copyright TARA Systems GmbH Page 104 Chora User Manual www embedded wizard de Statements TARA Systems get_page nr aIndex nrl nr2 Sendif Now the local variables are initialized and can be stored in a new PageNr object var Example PageNr pageNr new Example PageNr pageNr Nrl nrl pageNr Nr2 nr2 return pageNr Beside the local variables and method parameters the code enclosed within the native statement may also access members of this object Unlike the local variables and method parameters the access to these members presumes a deep understanding how Chora statements and expressions are translated into the language of the appropriate target system native this if this gt Super3 group 0 We do not recommend to access object members directly from the native code instead of this local variables should be used In this manner the native code is more unsusceptible to future changes in the Chora compiler Beside the native statement Chora also supports native methods see Native methods chapter 4 1 5 1 where the native method may contain the target specific code only the mixing with the Chora code is not possible Therefore we recommend the using of the native statement instead of the obsolete native methods 5 18 attachobserver statement The attachobserver statement registers a slot method as an observer for notifications triggered for a given
80. E composer true Pass this code if both conditions are true only Sendif Embedded Wizard Copyright TARA Systems GmbH Page 168 Chora User Manual www embedded wizard de Chora preprocessor TARA Systems Before the preprocessor can evaluate the expression in a if condition all macros contained in the expression are replaced by their contents gt See Macro evaluation chapter 8 1 This makes it very easy to control the code generation conditionally through the definition of macros For example the following chunk of code will pass the preprocessor only if the Debug macro in the currently selected profile contains the character string true Sif Debug true trace Menu Visible Menu Bounds Menu Caption Sendif In this case the expression can be further simplified if the Debug macro contains either the character string true or false Sif Debug trace Menu Visible Menu Bounds Menu Caption Sendif In comparisons using the or operator one of the both operands may contain special wildcards and The character stands for an arbitrary number of any characters including an empty string The wildcard on the other hand stands for exactly one character These wildcards are used like patterns in comparing character strings Sif Splatform Tara Win32 Pass this code for Win32 platforms only Sendif Only if the content of the platform macro begins with the string Tara Win32 is the if cond
81. EF a 12EF56FF The instant property blue corresponds to the blue value of the color The read access to this property returns this blue value and the write access changes it The other values red green and alpha are not affected var color a 123456FF var uint8 c Get the blue value c a blue c 0x56 change the blue value a blue OxEF a 1234EFFF The instant property alpha corresponds to the alpha value of the color The read access to this property returns this alpha value and the write access changes it The other values red green and blue are not affected var color a 123456FF var uint8 c Get the alpha value Copyright TARA Systems GmbH Page 149 www embedded wizard de Operators TARA Systems int32 rect xl int32 reet vgl int32 rect x2 Embedded Wizard Chora User Manual c a alpha c OxFF change the alpha value a alpha 0x00 a 12345600 The instant property x1 corresponds to the X1 left coordinate of the rectangle The read access to this property returns this coordinate value and the write access changes it The other coordinate values are not affected var rect a lt 10 20 30 40 gt var int32 c Get the x1 coordinate c a xl c 10 change the x1 coordinate a xl 0 a lt 0 20 30 40 gt The instant property y1 corresponds to the Y1 top coordinate of the rectangle The read access to this property returns th
82. Embedded Wizard Copyright TARA Systems GmbH Page 80 Chora User Manual www embedded wizard de Unit file EWU TARA Systems yvautoobject Core Timer Timer autoobject Core Timer 38 MenuCaption ariant vconst string 37 x Brick lt 430 310 570 350 gt Class Core Timer Description VariantCond true e VariantOf DemoMenu Timer Begin 0 Enabled false OnT rigger null x VYariantCond The variant condition attribute This attribute specifies the condition when the variant should be used in order to substitute the origin class constant or resource ancestor His Description 4 9 Comments All constants resources enumerations sets inline code definitions classes and their members may be commented Such comments are preceded by a double slash and extend to the end of the line of code This is the base class for all Menus class Menu Core Group Caption contains the string to draw in the title bar of the Menu property string Caption Unlike in other programming languages the comments are not ignored or simply bypassed but are read by the Chora compiler and output in the generated ANSI C code From the standpoint of Chora comments are fully valid syntactic elements Therefore it is not allowed to place a comment just anywhere in a unit file This excerpt from an erroneous unit file demonstrates this Embedded Wizard Copyright TARA Systems GmbH Page 81 Chora User Manual
83. GBA8888 Optimization Generator The optimization level attribute controls the code The code generation attribute determines how this generation Depending on the value of this selected member is handled by the Code attribute the Code Generator may perform Generator different code simplification and elimination steps If this attribute is true the affected member will be Following levels are available always translated by the Code Generator If this None No optimization is performed attribute is set false the affected member may be x Description a Description Embedded Wizard Copyright TARA Systems GmbH Page 192 Chora User Manual www embedded wizard de
84. OnSetData onset 125 Data property object 124 K AnimationSteps array point 123 e D FindNexttem method 127 9 OnGetData onget 126 H OnSetData onset 125 lt 30 390 170 430 gt Buck Data property object 124 xj Description Refers to the data source Eege ZER 139 Generator false Brick lt 30 440 170 480 gt Type object ell Description Default null Generator false Native false e Type The type of the variable property or an array Embedded Wizard expects here a valid Chora datatype or an expression which sl Native The native attribute determines whether this method contains a pure Chora code or the target dependent native code e g x Description 4 Description The logic of the onset onget method can be implemented in the Editor window after the method brick has been double clicked Embedded Wizard Copyright TARA Systems GmbH Page 33 Chora User Manual www embedded wizard de Unit file EWU TARA Systems onset DemoMenu MainMenu Data Hr 4 Any changes if C pure Data value return f f Remember the new data pure Data value ff Force an update Invalidate Q 4 1 4 Embedded objects Embedded objects are always introduced with the keyword object followed by the objects class the name and optional a set of initialization values presets of the object class Menu object Sample Item Iteml preset Caption Video Sett
85. SuperTimer called Please note that this process is automatically controlled by the Runtime Environment so that the use of the super call super is superfluous and even undesirable Use of the optional keyword native allows the constructors to be implemented in the form of native methods Since constructors are primarily intended for direct access to the hardware and operating system most constructors will thus be native methods See also native statement chapter 5 17 The 32 bit unsigned integer argument is used by the Runtime Environment and the Resource Manager whenever a resource is to be loaded into a resource object In this case the Resource Manager passes to the object the address of the resource that is to be loaded In all other cases including those involving objects created directly using the Chora keyword new the constructors are always called with 0 zero as an argument Unlike other methods the argument in the constructor is optional and may be omitted Embedded Wizard Copyright TARA Systems GmbH Page 51 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Please note that the definition of constructors given here may have to be amended for new platforms For more details see new operator chapter 7 6 4 1 5 6 Done destructors A destructor is a special kind of method with the preset name Done The destructor expects no arguments nor may it return a value class Timer method na
86. The optimization works without trouble as long as the eliminated variables or methods are not accessed from the outside of the Chora application For example it is a usual practice to call Chora methods directly from the C code in order to pass data from the target system to the GUI application Due to the fact that the Chora compiler does not know anything about the interface between the GUI application and the target system it is not able to recognize which methods and variables are accessed from the outside of the Chora world If not used elsewhere in the project the affected members are simply eliminated This results in unexpected and confusing C compiler and linker errors For this purpose Embedded Wizard supports an optional Soutput directive This directive can be placed in front of the affected class method variable etc definition in order to control the code generation for this member The output true directive forces for example the code generation independent of whether the affected member is used in the project or not In contrast to this the Soutput false directive disables the code generation unless the affected member is explicitly referenced from other also used parts of the application Therefore it is necessary to sign all classes variables methods etc which are accessed from the outside of the GUI application with the directive output true All other classes resources constants variables methods p
87. To suppress the carriage return a backslash sign should be used at the end of the text line In this case multiple lines are concatenated together to a single text block which will appear within a single HTML paragraph The HTML browser is then responsible for the text flow and the line wrapping occurs automatically This should be a very long long text line so it has to be continued in the next line to appear within a single paragraph This line appears in the next paragraph class Menu Forms Form 2 Identifiers started with the dollar sign are recognized as potential macros In the case the identifier is a valid macro name defined in your project a cross reference to this macro description is added to the text For example the following inline documentation will be extended by a cross reference to the description of the macro Size Set the bounds of the menu to the size of the screen defined in the macro Size inherited property Bounds rect lt 0 0 gt Size Embedded Wizard Copyright TARA Systems GmbH Page 187 Chora User Manual www embedded wizard de Comments TARA Systems 3 Identifiers separated by the double colon are recognized as a potential name of a class constant resource or enumeration In the case the name belongs to an existing definition within your project a cross reference to the description of this definition is added to the text For example the fo
88. Wizard Copyright TARA Systems GmbH Page 185 Chora User Manual www embedded wizard de Garbage collection TARA Systems method void Done By the following assignment this object becomes reachable again Don t do this AnOtherReachableObject Link this A further issue relating to garbage collection is the point in time when it is started In most target systems this point is random and thus not predictable This means that an object s destruction can be delayed Although the Garbage Collector guarantees that all unused objects are disposed of the time of the disposal is not known This limitation is not actually a problem In a few cases however it can become problem when an object is supposed to release a particularly scarce system resource in the destructor The delay can result in a temporary unavailability of important system resources In such a very rare case we recommend implementation of a Close or Free method which explicitly invoked can release the scarce system resource and do it long before the Garbage Collector could dispose the object Because destructors are used almost exclusively in driver classes the typical GUI application programmer is spared the consequences described here Embedded Wizard Copyright TARA Systems GmbH Page 186 Chora User Manual www embedded wizard de Comments TARA Systems 12 Comments Unlike other programming languages in Chora comments are fully valid syntac
89. __send_i2c Audio OFF Sendif if Sprofile Chassis2 AudioOff Sendif By using the Sif else Selseif and S endif Chora preprocessor directives part of the code block depending on the target platform can be ignored or taken over If the condition in an if or Selseif directive is fulfilled is true the following part of the code block is taken over If the condition is not fulfilled the code block is ignored Details of the Chora preprocessor are found in Chora preprocessor chapter 8 Beside the native methods a more powerful native statement is available in Chora The statement allows the mixing of Chora code and the target specific code within the body of one and the same method For more details see native statement chapter 5 17 Within the Embedded Wizard IDE the native method attribute can be set in the Inspector window when the appropriate method has been previously selected Brick lt 390 240 530 280 gt Description Searches for the next menu i Generator false Native true mj 4 1 5 2 onget methods onget Methods are always introduced with the keyword onget followed by the name of the corresponding property and the logic the body of the method Embedded Wizard Copyright TARA Systems GmbH Page 43 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class Menu property color Color 000000FF onget Color Get the value from memory return pure Colo
90. a type This data type contains a reference to a Chora class This reference can then be used in order to create objects of this class dynamically var class theClassl classof otherObject var class theClass2 Views Text var object theObjectl new theClass1 var object theObject2 new theClass2 The class data type provides a very powerful construct which can be used to create for example object factories Details on the creation of objects are described in new operator chapter 7 6 In order to obtain the class of an existing object the operator classof is available See classof operator chapter 7 13 object Object data type This data type represents all classes defined in a Chora program A variable of type object can therefore store a reference to an object of any class without the Chora compiler reporting a data type mismatch error when this variable is assigned var object theObject new Sample Item Ok theObject new Audio Device Ok theObject new Core Timer Ok theObject null Ok The object data type is analogous to a universal generic class which means that it can t be used in the context of object methods properties variables and so on The Chora compiler is not capable during the Embedded Wizard Copyright TARA Systems GmbH Page 116 Chora User Manual www embedded wizard de Data types TARA Systems translation of recognizing the class behind an object In some cases this class
91. aMode For more details about the output directive see Control directives chapter 8 3 Within the Embedded Wizard IDE the methods appear as bricks in the Class Composer window The icon in the brick depends on the kind of the method In case of generic methods following brick is displayed The attributes of the method can be set directly in the Inspector window when the appropriate method s brick has been previously selected D FindNexttem method 19 OnGetData onget 126 E OnSetData onset 125 Data property object 124 BS a i a a T Ke bei sl Brick lt 390 240 530 280 gt Description Searches for the next menu i Generator false Native false v Native The native attribute determines whether this method contains a pure Chora code or the target dependent native code e g v Description bai The declaration and the logic of the method can be implemented in the Editor window after the method brick has been double clicked Embedded Wizard Copyright TARA Systems GmbH Page 41 Chora User Manual www embedded wizard de Unit file EWU TARA Systems method Forms Ctr DemoMenu MainMenu FindNexttem arg Forms Ctrl aCtrl arg bool GI aOnlyEnabled method Forms Ctrl FindNexttem arg Forms Ctrl at Hl arg bool aOnlyE nabled gt ar Core View view var int32 count ff The view has to belong to the group if CC view null amp C view group this throw Th
92. aiement e da TE a E REDRE 95 Embedded Wizard Copyright TARA Systems GmbH Page 2 Introduction TARA Systems Chora User Manual www embedded wizard de 510 return SNEME 2 cscs cetey escent eege eege ege dE SEENEN 96 Dil 1 signal STALCMEML EE 97 DEENEN E EE 98 5 13 itdlesignal statement nsira aatinaa daa eai aandaa degen 99 E throw exception UE 101 5 15 trace debug statement siinide ene daddies ENEE SEENEN 102 5 16 tracestack debug statement ceccec ce ceseceece cece eeeeaeeeeaaeeeneeeseaeeseaaeseeaeeseeeesaeeeeaaesseneeeea 102 Delf native siate menl eeeseksgusgegegedeg e do anne edn nea de nebo asp see tn pee ee te 102 5 18 attachobserver Stee n eessen Ges dien Zeeche Sege ed 105 5 19 detachobserverx Slatepentteeugeetedee ee ee Eed 108 5 20 notifyobservers Siaiement irinna innan iaaa aani daana iaaa iana 109 6 D t YPES car ae soccer ere cident era tee eee 112 GE Rue E Bee 112 6 2 User defined data types AA 117 6 3 Reference data types 0 cccecccecceeeenceceeeeecaeeeeaaeeeeneecaeeeeaaeseeaaeegaeeeseaeeseaaesseaeessaeeesaeseeaaesseneeee 118 EE ee 120 7A Unary instant operators saussaie gees eEi ageet eege de 121 7 2 Binary instant OPCrators cc cc ceceeeeeeceeeeeeeaeeeeaaeeeeeeeceaeeeeaaeedeaaesaeeeseaeeseaaeseeaeeseeeeesaeeseaaesseneeead 123 7 3 Instant Cast operators seissen Eege REESEN 133 7 A Object CASE ee EE 135 Lo enom ANG geet te CEET 138 7 6 Ne TEE 139 FA INSANE constrict S ese E EE ER 141 T8 In
93. al string will be unchanged var string a HEllo var string c c a lower c hello This instant property is read only You can t assign any values to lower The read access to the instant property length of a string returns the number of characters contained within this string If the string is empty the property returns 0 var string a Hello World var string b var int32 oc fi 12 ces 0 c a length c b length This instant property is read only You can t assign any values to length The instant property red corresponds to the red value of the color The read access to this property returns this red value and the write access changes it The other values green blue and alpha are not affected Copyright TARA Systems GmbH www embedded wizard de Page 148 Operators TARA Systems uint8 color green uint8 color blue uint8 color alpha Embedded Wizard Chora User Manual var color a 123456FF var uint8 c Get the red value c a red c 0x12 change the red value a red OxEF a EF3456FF The instant property green corresponds to the green value of the color The read access to this property returns this green value and the write access changes it The other values red blue and alpha are not affected var color a 123456FF var uint8 c Get the green value c a green c 0x34 change the green value a green Ox
94. ally the vautoobject definition may be prefixed with the S variant directive This directive determines the condition when the variant is used in order to substitute its origin auto object the variant is used only if the condition of the directive is fulfilled For example the following variant is used if the Win32 profile is selected for the code generation In all other cases the variant is ignored Svariant Win32 vautoobject AudioLoud TheUnit Audio The Svariant directive allows the implementation of multivariant auto obejcts A single auto object can be overridden by multiple variants Which variant is finally used is determined during the code generation and at the runtime In this case we distinguish between static and dynamic variants Static variants depend on profiles and dynamic variants on styles For more details about the Svariant directive see Control directives chapter 8 3 In Chora it is also possible to derive an auto object variant from another auto object variant This results in very powerful instrument for the development of multivariant GUI applications Within the Embedded Wizard IDE auto object variants appear as auto object bricks extended by a small icon in the Unit Composer window vautoobject Core Timer i N TimerVariant F The attributes and properties of the auto object variant can be set directly in the Inspector window when the appropriate variant brick has been previously selected
95. an The result is true if the left string operand is lexicographically less than the value of the right string operand var string a cold var string b cool var bool c c a lt b c true Greater than The result is true if the left operand is greater than the value of the right operand Both operands must be arithmetic var int32 a 1369 var int32 b 1251 var bool c c a gt b c true Greater than The result is true if the left string operand is lexicographically greater than the value of the right string operand var string a cold var string b cool var bool c c a gt b c true Less than or equal to The result is true if the left operand is less than or equal to the value of the right operand Both operands must be arithmetic var int32 a 1369 var int32 b 1369 var bool c c a lt b c true Less than or equal to The result is true if the left string operand is lexicographically less than or equal to the value of the right string operand var string a cold var string b cold var bool c c a lt b c true Copyright TARA Systems GmbH Page 131 www embedded wizard de Operators TARA Systems gt int gt int Greater than or equal to The result is true if the oo left operand is greater than or equal to the value of the right operand Both operands must be arithmetic var int32 a 1369 v
96. aption MyMenu MyCaption Like a real constant a constant variant may store multiple language dependent values Similarly to the class inheritance a constant variant inherits all values from its ancestor If necessary the inherited values can be modified or new values can be added const string Caption Default Hello German Guten Tag 1 veconst MyCaption Menu Caption Default Good Morning French Bonjour 1 In the example above the variant MyCaption extends the origin constant by a new value for the language French and overrides the inherited default value from Hello to Good Morning The value for the German language still keeps unchanged From the programmer s point of view the constant Caption contains now 3 language dependent values Please note the language French is new added to the constant In this way the customer can customize existing constants and adapt them to new languages The choice of the appropriate language dependent value of a constant happens at the runtime of the Chora program and is completely transparent to the programmer The programmer needs only to switch between the languages in order to set all constants to a value suitable to the language chosen More details in Language selection chapter 9 The concepts of language dependent and multivariant constants do complement one another gt see Usage of Variants chapter 10 Beside the few differences des
97. ar Core View theView var Sample Item item item Sample Item theView Once used the object cast operator returns the unchanged object if the object is derived from the target class given In the case that the object is not derived from the target class nu11 null object is returned An object is derived from a class only if this class appears in the object s inheritance hierarchy The following illustration gives an example of a simple inheritance hierarchy consisting of 4 classes The class Core View is the original base class Starting from this original base class Core Group was derived Core Group in turn serves as the base class for classes Sample Item and Sample Menu Embedded Wizard Copyright TARA Systems GmbH Page 135 Chora User Manual www embedded wizard de Operators TARA Systems Figure 7 2 An object of class Sample Item therefore derives from the classes Core View Core Group and Sample Item The class Sample Menu on the other hand exists outside this object s inheritance hierarchy so that the object cast operator fails in the conversion from Sample Item to Sample Menu and returns null var var var var var obje Core Core Samp Sampl theView theGroup theItem theMenu et le e View Group Item Menu Core Core item new Sample Item theView theGroup theltem theMenu View item Group item Sample
98. ar Sample Menu theObject new Sample Menu Signal theObject OnAction Signals and slot methods exist for simple communication A receiver object is informed that an event has happened The transmission of additional data is not necessary Only the identity of the sender object can be evaluated For this purpose each slot method contains a hidden argument named sender through which access to the broadcast object can be obtained If a slot method is to receive signals from different sources sender can be used to verify the source of a signal Embedded Wizard Copyright TARA Systems GmbH Page 47 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class Menu Two embedded objects which can send signals to the OnAction slot object Sample Item Iteml1 object Sample Item Item2 slot OnAction if sender Iteml Do something in response to the signal from Iteml object if sender Item2 Do something in response to the signal from Item2 object Except for the definition using the keyword slot there is no difference between a slot method and a normal method All slot methods are automatically inherited in class derivation and can be overridden in the derived class class SubMenu Sample Menu object Sample Item Item inherited slot OnAction if sender Item Do something in response to the signal from the Ite
99. ar int32 b 1369 var bool c c a gt b c true am string gt string Greater than or equal to The result is true if the left string operand is lexicographically greater than or equal to the value of the right string operand var string a cold var string b cold var bool c c a gt b c true Table 7 2 The operators may be used to join an arbitrary number of operands in an expression The Chora compiler does not define a limit for this Please note that the data types of the operands used must be suited to the operators Thus the following operation is not valid and will result in an error message from the Chora compiler var rect Rectl lt 0 0 200 100 gt var rect Result Result Rectl Hello world This example contains at least one error The operator has been used with a rect and a string operand The Chora programming language does not however define a operator with which a rect and a string operands may be combined As a result this expression causes a Chora compiler error message The expressions are generally evaluated from left to right whereby partial expressions in parentheses are evaluated first so that the result of the partial expression can be used in the overall expression as operand If the parentheses are missing the order of evaluation within a complex expression is determined by the precedence of operators The following priorities exist fo
100. are meaningful A rect can t be converted to a point for example In such a case the Chora compiler will produce an error message It must also be noted that a type conversion can be lossy For example converting the signed integer int 32 to an unsigned integer uint16 results in not only the loss of the sign but also the loss of the upper 16 bits of the number gt Object cast operators gt An object cast operator is used to check whether an object is derived from a particular class Due to the polymorphic nature of the objects in most cases the Chora compiler can t predict which class the objects used in the program will have at runtime The object cast operator allows the programmer to verify the class of an object gt Enum and set cast operators gt A special kind of cast operators which allow the programmer to convert a number operand into an enum or set operand and vice versa Unlike other programming languages Chora handles the conversion very strictly and ensures that the conversion remains legal In this manner it avoids erroneous conversions of numbers into an enum or set operand Embedded Wizard Copyright TARA Systems GmbH Page 120 Chora User Manual www embedded wizard de Operators TARA Systems gt new operator gt The new operator is necessary to create objects of a desired class at the runtime For example the expression new Views Text creates and initializes a new object of this Views Text class Each object
101. are destroyed Here the Garbage Collector wanders through the entire memory heap and searches for objects that were not marked during the first phase These objects are then destroyed Objects are also destroyed in 2 steps gt First the object in question must be de initialized To do this the Garbage Collector invokes the object s destructor The destructor gives the object a chance to release all system resources previously reserved or to restore the state of the hardware the object controls Details on destructors can be found in the chapter Done destructors chapter 4 1 5 6 gt When the destructor is finished the memory taken up by the object is released and can be used for other objects An important feature of the Garbage Collector is the 100 certainty that only unused and unreachable objects are disposed of An object is unreachable when there is no any references in the entire GUI application that could refer to that object Only then can the object never again be accessed and be disposed of as garbage For this reason it is important to understand that under no circumstances may one use one object s destructor to access other objects In some cases that makes the object that is being destroyed reachable again At such time the object s ongoing destruction can no longer be avoided The result is an unpredictable malfunction in the GUI application The following code demonstrates what not to do in a destructor Embedded
102. arrays are always introduced with the keyword array followed by the data type the name the size and optional a set of initialization values of the array class Menu array int32 Counters 8 array string Captions 2 Default 0 Video Settings Default 1 Sound Settings JI In this example the definition of the Menu class has been given two arrays Counters and Captions The data type of the Counters array int32 determines that the array can store 32 bit signed integer values The second array Captions on the other hand stores only string values that is series of characters Unlike a variable an array can store more than one value To do this the maximum size of an array must be given explicitly in its definition In this case the size of the two arrays was limited to 8 and 2 respectively The Counters array can thus not store more than 8 values Embedded Wizard Copyright TARA Systems GmbH Page 26 Chora User Manual www embedded wizard de Unit file EWU TARA Systems An array does not necessarily have to be initialized at the time of definition In our example only the Captions array was given initial values namely Video Settings and Sound Settings If an object of class Menu is created at runtime the object s Captions array is automatically initialized at the time of creation so that the first element of the array 0 is given the character string Video Settings and the second element 1 the
103. ation of condition expression step 2 4 If the condition is false execution of the for statement terminates and control passes to the next statement in the program No loop expression is evaluated The following example uses a for loop to compute the average of all five elements of the array numbers var int32 inx array int32 numbers 5 var int32 average for inx 0 inx lt 5 inx inx 1 sum sum numbers inx average sum 5 5 9 while iteration statement The while statement executes an expression and a statement repeatedly until the value of the expression is false The syntax for the while statement while expression statement The expression must be of type bool otherwise a Chora compiler error occurs Execution proceeds as follows 1 The expression is evaluated 2 If the expression is initially false the body of the while statement is never executed and control passes from the while statement to the next statement in the logic 3 If the expression is true the body of the statement is executed and the process is repeated beginning at step 1 Embedded Wizard Copyright TARA Systems GmbH Page 95 Chora User Manual www embedded wizard de Statements TARA Systems The following example uses the while statement to copy all 5 elements of array listi into array list2 The while statement is run through repeatedly until the condition inx lt 5 is no longer fulfilled gt that is
104. be improved in the future to include new resources e g sound animated GIFs etc The current version of the Chora compiler contains only a bitmap and a font resource converter Optionally the resource definition may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Soutput true resource Resources Bitmap Logo For more details about the output directive see Control directives chapter 8 3 Embedded Wizard Copyright TARA Systems GmbH Page 58 Chora User Manual www embedded wizard de Unit file EWU TARA Systems In Chora it is possible to override a resource by so called resource variants Resource variants provide a powerful technique for the extension and adaptation of resources Each time a resource is used Embedded Wizard determines automatically the appropriate variant and uses it instead gt for more details see Variants chapter 4 8 4 3 1 Attributes of a bitmap resource A resource of the class Resources Bitmap supports the following attributes Attribute name FileName AlphaName Embedded Wizard Chora User Manual Description This attribute contains the name of a bitmap file containing the bitmap color information The following image file formats are supported BMP PNG GIF and JpPG The resource converter will read this file and convert the bitmap pixel da
105. be substituted by derived variants gt Classes gt In the derived class variant the inherited members can be adapted new members can be added and existing methods can be overridden in order to change the behavior of the class gt see Class Variants chapter 4 8 1 gt Constants gt In the derived constant variant the inherited language dependent values can be modified and new language variants can be added to the constant gt see Constant Variants chapter 4 8 2 gt Resources gt Similarly to the constant variants the language dependent values of a resource can also be modified or extended gt see Resource Variants chapter 4 8 3 gt Auto objects gt In derived object variant the inherited properties can obtain modified initialization values gt see Auto object Variants chapter 4 8 4 By using variants the origin substituted definition itself does always remain unchanged and all desired modifications are implemented in the derived variants only This simplifies the customization process significantly The customer can now adapt the GUI application to his requirements without the necessity of any modifications on the software delivered by his supplier Embedded Wizard Copyright TARA Systems GmbH Page 71 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Unlike the ordinary class inheritance each variant is signed with a variant condition This condition determines when the variant w
106. bservers notifyobservers null Embedded Wizard Copyright TARA Systems GmbH Page 110 Chora User Manual www embedded wizard de Statements TARA Systems In order to provide several independent groups of global observers the optional id operand has to be used The notifyobservers statement expects here a uint32 expression The result of this expression allows an additional subdivision of observer groups In the following example the slot methods are attached as observers for two different global notifiers The identity of these notifiers is specified by the last operands First register two observers attachobserver updateThis null 1 attachobserver updateThat null 2 Then notify the observers with the ID 2 In response to this the slot method updateThat will receive a signal updateThis will not notifyobservers null 2 The optional id operand can also be used together with an object or a property reference In this case several independent groups of observers may exists all attached to one and the same object or property The determination of the affected group is performed on the basis of the optional id operand notifyobservers controller 1369 If the optional operand is missed the value 0 zero is assumed automatically Embedded Wizard Copyright TARA Systems GmbH Page 111 Chora User Manual www embedded wizard de Data types TARA Systems 6 Data types Knowledge of
107. by which an enum or a set operand is converted into a number operand or vice versa The following example demonstrates the conversion of an enum operand into an int32 number operand var Graphics AlignH align var int32 number align Graphics AlignH Center number int32 align The resulting value of the conversion depends on the appropriate enum definition If not explicitly specified the items of an enum definition are enumerated automatically starting with the value 0 for the first item 1 for the second and so far Assumed that Center is the second item within the Graphics AlignH definition the conversion would return the value 1 For more details see Enumerations chapter 4 6 The next kind of possible conversion works in the reverse direction With this cast operator it is possible to convert a number into a specified enum operand var Graphics AlignH align var int32 number number 1 align Graphics AlignH number This cast operator evaluates the spefified enum definition and verifies whether there is an item which does correspond to the given number If yes the operator returns the affected item gt in our example Graphics AlignH Center is returned If the enum definition does not contain any corresponding item the cast operator failes and a runtime error is reported In the same manner as described above with the enum definitions Chora also provides cast operators for the conversion of set opera
108. cally var Sample Menu theObject new Sample Menu theObject Color FFOOFFFF The assignment to the Color property shown in the example automatically invokes the corresponding onset method of the Color property The assigned value is passed on to the method in a hidden argument named value Within the onset method you can evaluate value and change it in order to react to changes in the property You can for example query the validity of the assigned value and if necessary adjust the invalid value Embedded Wizard Copyright TARA Systems GmbH Page 45 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class Menu property color Color 000000FF onset Color No transparency allowed if value alpha lt 255 value alpha 255 Store the new value in the memory pure Color value If the property s new value is to be stored you must place the contents of value directly in memory using the keyword pure The above example demonstrates the usage of pure keyword and the hidden value argument An onset method can t return any values Except for its definition using the keyword onset there is no difference between an onset method and a normal method All onset methods are automatically inherited in class derivation and can be overridden in the derived class class SubMenu Sample Menu inherited onset Color Pass the value to the base class ve
109. can be set directly in the Inspector window when the appropriate brick has been previously selected Embedded Wizard Copyright TARA Systems GmbH Page 66 Chora User Manual www embedded wizard de Unit file EWU TARA Systems LanguageMenu class Menu Menu 1 MainMenu class Menu Menu bott MenuCaption const string 24 _ Inline inline 25 a lt 30 70 170 110 gt This is an inline code block true e Brick Description Generator Generator The code generation attribute determines how this selected member is handled by the v Description bai The content of the inline code block can be implemented in the Editor window after the block s brick has been double clicked inline DemoMenu Inline Ei include ewtimer vr This local procedure will be called when the OS timer is expired so the routine invokes the Core Timer Trigger method of the timer object SE woid TimerProc XUInt32 arg CoreTimer_Trigger CoreTimerjaa rg 4 6 Enumerations Enumerations are always introduced using the keyword enum followed by the name of the enumeration itself enum AlignH item Left item Center item Right Here we have defined a new enumeration named AlignH The enumeration consists of 3 elements so called enumerators with the names Left Center and Right An enumeration is a user defined data type This data type may be used to declare variables that may have a specific value giv
110. can even be changed at runtime through a assignment to the object variable For this reason any attempt to use a variable method property etc in the context of object leads to an error message var object theObject new Sample Item theObj ect Visible true Error Only an explicit dynamic object cast guarantees that the generic object data type can be casted in a particular class After the object cast has been performed successfully the members of the object may be accessed var object theObject new Sample Item Sample Item theObject Visible true Ok Note that the object cast does not apply any sort of transformation to the object Instead it merely performs a comparison between the object s class and the desired class If the object cast fails the expression returns null leading to a runtime error if the following security check is missing var object theObject new Sample Item if Sample Item theObject null Sample Item theObject Visible true Further information about the object cast is found in Object cast operators chapter 7 4 Table 6 1 A big advantage of instant data types lies in the predefined instant operators With the help of these operators the programmer can construct complex expressions with string rect point etc operands For example he can combine two character strings into one using the operator var string Textl Hello va
111. cause each object stores its own copy of its array it is not possible to define global arrays in Chora Changing an object s array has no effect on the arrays of other objects var Sample Menu objectl new Sample Menu var Sample Menu object2 new Sample Menu theObject1 Captions 0 Brightness Thus if as the above example demonstrates at runtime the first element of the Captions array of objecti is altered this has no effect on the content of the second object object2 Its Captions array still contains the original initialization values Video Settings and Sound Settings Embedded Wizard Copyright TARA Systems GmbH Page 27 Chora User Manual www embedded wizard de Unit file EWU TARA Systems When classes are derived all arrays defined in the base class are automatically inherited by the new class The derived arrays do not have to be redefined unless the programmer wishes to change the initialization values of an array Then and only then the definition of the inherited array can be restated and initialized with different values class SubMenu Sample Menu inherited array Captions CH II Brightness 1 Contrast Default Default Note the use of the keyword inherited Each inherited array that is to be re initialized in the derived class must be introduced using the keyword inherited If this keyword is missing the Chora compiler will give an
112. cessor directives if Sprototyper Some Chora code to execute in the prototyping environment only Selse native dispatch command CMD UPDATE TUNER send _i2c_command Sendif By using the Sif else Selseif and S endif Chora preprocessor directives part of the code block depending on the target platform can be ignored or taken over If the condition in an if or Selseif directive is fulfilled is true the following part of the code block is taken over If the condition is not fulfilled the code block is ignored Details of the Chora preprocessor are found in Chora preprocessor chapter 8 Usually the code enclosed in the native statement needs an access to the environment in which it is implemented it should be able to read and modify local variables and method parameters To ensure the desired variables and parameters are accessible from the native code their names should be placed in the declaration part of the native statement method Example PageNr GetPageNr var int32 aIndex Declare some variables to share between Chora and the native code var int32 DEL var int32 nr2 In case of the prototyper initialize the both local variables properly Sif Sprototyper nri js nr2 In case of the target system call a function which is then responsible for the initialization of the local variables Selse native nrl nr2 aIndex Embedded Wizard
113. changed Each property has its own onset method Using an onset method the programmer has the means to react to the changing of a property slot methods gt A specialized method that can handle signals from other objects Signals exist for the sake of simple communication between objects If an object sends a signal to a particular slot of another object the logic of the corresponding slot method of the recipient object is automatically executed Init constructors gt Constructors are special methods that are automatically invoked in order to complete the initialization of an object Usually objects are initialized only by assigning values to the object s variables and properties In rare cases it may however be necessary for an object to execute additional code during its initialization For example thanks to a constructor each newly created timer object is automatically registered by the operating system in order for it to be able to receive the timer events Done destructors gt Destructors are special methods that are automatically invoked shortly before an object is destroyed in order to give the object the chance to release system resources that it is no longer using The Chora programming language has a Garbage Collector that automatically handles the disposal of unused garbage objects but in rare cases when an object has itself reserved a system resource this resource must be properly released when the object is destroyed For
114. cribed above the approach of the definition of a constant variant does not differ from the one of a real constant as this is described in Constants chapter 4 2 Optionally the vconst definition may be prefixed with the Svariant directive This directive determines the condition when the variant is used in order to substitute its origin constant the variant is used only if the condition of the directive is fulfilled For example the following variant is used if the Win32 profile is selected for the code generation In all other cases the variant is ignored Svariant Win32 veonst MyCaption Menu Caption Embedded Wizard Copyright TARA Systems GmbH Page 75 Chora User Manual www embedded wizard de Unit file EWU TARA Systems The Svariant directive allows the definition of multivariant constants A single constant can be overridden by multiple variants Which variant is finally used is determined during the code generation and at the runtime In this case we distinguish between static and dynamic variants Static variants depend on profiles and dynamic variants on styles For more details about the variant directive see Control directives chapter 8 3 In Chora it is also possible to derive a constant variant from another constant variant This results in a very powerful instrument for the development of multivariant GUI applications and it simplifies the customization of existing software Within the Embedded Wizar
115. d the signal will be delivered In the same manner as it has been demonstrated in the examples above a slot method can also be detached from an object In this case the detachobserver statement expects an expression which results in an object detachobserver update controller If one of the expressions specified in the detachobserver statement results in a null value the observer is not de registered and the program execution is continued without any error messages var slot theSlot null var object theObject null detachobserver theSlot theObject This should not be mixed with the third form of the detachobserver statement where the null value is passed explicitly as the second operand of the statement This form of the statement is designed especially for the de registration of global object and property independent observers detachobserver update null In order to provide several independent groups of global observers the optional id operand has to be used The detachobserver statement expects here a uint32 expression The result of this expression allows an additional subdivision of observer groups In the following example the slot methods are detached from two different global notifiers The identity of these notifiers is specified by the last operands detachobserver updateThis null 1 detachobserver updateThat null 2 The optional id operand can also be used together with an object o
116. d Copyright TARA Systems GmbH Page 156 Chora User Manual www embedded wizard de Operators TARA Systems array string Items 16 var char Cs Eeer 10 Hello World c Items 10 0 7 C 1H C Items 10 1 i C Zei C Items 10 11 IJ Cas Vr The following example demonstrates the use of the index operator in order to convert all characters in all strings from upper to lower case array string Items 16 J var int32 ate var int32 12 All strings in the array Items are converted to lower case character by character for il 0 il lt 16 il il 1 for i2 0 i2 lt Items il length i2 i2 1 Items il i2 Items il i2 lower The index operator can also be used in a complex expression if the expression results in a string and one wish to query a character within this string var char c c Hello GetUserName 6 J Unlike reading a character modifying a character within a string is possible only with limitations If the string is a literal a constant or an expression the string can t be changed an assignment is not possible var char CF var string text Hello World Assignment Hello GetUserName 6 Syntax error Hello 4 ki Syntax error Sample TheStringConstant 0 Syntax error text 0 h Ok Read access c Hello GetUs
117. d IDE constant variants appear as constant bricks extended by a small icon in the Unit Composer window The attributes of the variant can be set directly in the Inspector window when the appropriate variants brick has been previously selected 3 MenuCaption ariant yconst string ER MenuCaption const string 36 MenuF ont ariant vresource Resources Font 36 sl Brick lt 405 390 595 430 gt ConstantT ype string Description YariantCond tru d x VariantOf DemoMenu MenuCaption E Values Main Menu Default Main Menu German Hauptmen YariantCond The variant condition attribute This attribute specifies the condition when the variant should be used in order to substitute the origin class constant or resource ancestor x ry Description 4 8 3 Resource Variants Resource variants are always introduced by the keyword vresource followed by the name of the variant and the name of the origin resource its ancestor Embedded Wizard Copyright TARA Systems GmbH Page 76 Chora User Manual www embedded wizard de Unit file EWU TARA Systems vresource MyLogo Menu Logo attr FileName MyLogo png Using this definition we have created a variant MyLogo of a resource Menu Logo The variant inherites all resource attributes and their language dependent values from the origin resource and overrides the default value of the attribute FileName with MyLogo png Please note
118. d be applied Embedded Wizard Copyright TARA Systems GmbH Page 113 Chora User Manual www embedded wizard de Data types TARA Systems var char theNewLineChar n string A string of characters Each character occupies 16 bit in memory so it is possible to encode all known characters Use of the worldwide character encoding standard UNICODE is possible A character string is always enclosed by a set of double quotes H the character string contains no characters it is the so called empty string consisting only of two double quotes var string DayOfTheWeek Friday var string EmptyString If a character string must contain characters that can t be entered directly from the keyboard these characters can be expressed in hexadecimal notation by using the x escape sequence var string Text x1l001 x6CA9 Text In this way one is able to enter individual characters of a foreign language such as Japanese without having to depend on that keyboard or input machine Please note that the x escape sequence always expects to be followed by 4 hexadecimal digits The following list shows the entire set of supported escape sequences Each sequence always starts with a backslash sign The Chora compiler will automatically replace each found escape sequence with the corresponding character code a 0x0007 BEL Alert b 0x0008 BS Backspace f Ox000C FF Formfeed n 0x000A LF Newline r
119. d start with the Sversion directive followed by the appropriate definition Sversion 5 0 Description of the class class Timer An additional DIR file within the directory has to contain the list of the appropriate include files This file should also start with the Sversion directive followed by a list of include directives one for each include file Note the file names are without the extension Sversion 5 0 Sinclude View Sinclude Group Sinclude Root Sinclude Timer The unit splitting improves the simultaneous development of large units within a team of developers In this case each developer can work with it s own class constant resource etc include file Only the DIR file may need a manual adaptation in order to consolidate changes made by different developers 4 1 Classes Classes are always introduced by the keyword class followed by the name of the class Embedded Wizard Copyright TARA Systems GmbH Page 20 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class Shape var rect Bounds lt 0 0 128 64 gt var color Color FFOOOOFF method void Draw Do something to draw the shape Using this definition we have created a simple class containing two variables attributes Bounds and Color as well as one method Draw This class was derived from no other base class That means that aside from these two variables and the single method no other
120. d their embedded objects retain their original initialization values var Sample Menu objectl new Sample Menu var Sample SoundMenu object2 new Sample SoundMenu In this example the first object an object of class Sample Menu still contains the original initialization value for its embedded object Item1 The second object on the other hand has been instantiated by the derived class Sample SoundMenu In this case the Caption property of the embedded object will contain the value Sound Settings Within the Embedded Wizard IDE non graphical objects appear as bricks in the Class Composer window object Ettects colorEtfect ColorEffect l In case of graphical objects the objects appear as this is done on the screen in the target system the filled rectangle object is drawn as a filled rectangle a menu item object appears as a menu item etc Embedded Wizard Copyright TARA Systems GmbH Page 35 Chora User Manual www embedded wizard de Unit file EWU TARA Systems The attributes of the object can be set directly in the Inspector window when the appropriate object s brick has been previously selected E AnimationSteps array point 123 IsActivated var bool 122 wi ColorEffect object Effects ColorEff 121 Sheep object Sheep Sheep 120 x Brick lt 340 190 480 230 gt Class Effects ColorEffect e Description This is a pulse color effect Generator false Actor null
121. demonstrates how the both styles Aqua and WideScreen are activated simultaneously styles Aqua WideScreen To deactivate all styles simply assign an empty set to the styles variable styles The assignment to the variable styles does affect the following operations only Expressions evaluated already in the past are no more affected by the switch The following example demonstrates it The both variables text1 and text2 are initialized with the value of the constant Menu Caption text1 variable will receive and keep the origin non substituted value of the constant The second expression is evaluated after the style AquaLook has become active In this case the second variable text2 will receive the value overridden in the variant MyCaption var string textl var string text2 Ensure the styles are deactivated and get the value of the constant styles textl Menu Caption Activate the style and get the value of the constant styles Aqua text2 Menu Caption Embedded Wizard Copyright TARA Systems GmbH Page 181 Chora User Manual www embedded wizard de Usage of Variants TARA Systems The content of the styles variable can of course also be evaluated in an expression in order to query the currently active styles For this purpose Chora implements several operators For example the instant method contains determines whether a styles set contains another styles set If this is fulfilled
122. describes the desired quality of the converted font The programmer can choose between Low Medium and High High quality improves the readability of the font through anti aliasing but raises the memory requirement of the font resource Quality is only a suggestion Whether the font is indeed anti aliased is determined by the resource converter The Height attribute defines the desired height of the font in pixels The Bold attribute controls the weight of the font If this attribute is set true a bold version of the font is converted The Italic attribute determines whether an italic version of the font should be converted The attribute expects a true or a Copyright TARA Systems GmbH Page 61 www embedded wizard de Unit file EWU TARA Systems AspectRatio Ranges false value The AspectRatio attribute defines the desired aspect ratio of the font in the range from 0 25 to 4 0 The default value is 1 0 in this case the aspect ratio of the converted font corresponds to the origin design of the font With the attribute Ranges a set of characters can be specified for the font conversion Only the characters listed in this attribute are affected The simplest set consists of a single character e g 0 To define a range of characters the first and the last character has to be specified e g 0 9 Instead of the character literals it is also possible to use the x hexadecimal notation e g x0030 x003
123. dex operator Using an index operator it is possible to read a character from a string or to change a character into a string When a character is to be accessed the number the index of the desired character must be given in brackets var string Text Hello World var char Cy var int32 inx 5 C Text 0 l OS TE C Text 1 ii G Zei C Text 11 Ii CS Text Ans 1 The characters in a string are always counted from 0 zero Thus the first character is number 0 the second number 1 and so on Access to a nonexistent character causes an error at runtime Thus it is not possible as in C C to access characters outside of a string var string Text Hello World var char CF C Text 0 Ok C Text 11 Ok C Text 12 Ok gt returns zero terminator x0 C Text 13 Syntax or runtime error C Text 1 Syntax or runtime error It is recommended that the instant property length of a string be evaluated before the index operator is used on the string The instant property length returns the number of characters in a string var string Text Hello World if Text length gt 0 Text 0 Use of the index operator is similar to an access to a 1 dimensional array In order to access a character in a string array the index to the array and the index of the desired character must be given one after the other in brackets Embedded Wizar
124. e and has a fixed value defined by the programmer Using this name the value of a constant can be used in the Chora program Constants are excellently suited to defining for example menu titles or the colors of an GUI Changing a constant therefore affects the entire GUI gt Resources gt Resources are constant files that the Chora compiler adopts in the ANSI C code generated Thus it is possible for example to embed bitmaps or fonts in the GUI in order to use them at runtime from the GUI and display them on the screen gt Inline Code gt Inline is a special definition that makes the Chora compiler insert a native code sequence in the generated ANSI C code In this manner the combination of Chora and ANSI C code is possible This technique is used primarily in developing driver classes geared to specific platforms Such driver classes form the interface between the GUI and the underlying target system and guarantee the platform independence of the GUI that has been developed gt Enumerations gt An enumeration is a user defined data type that consists of a list of constant labels so called enumerators A variable of the type of such an enumerator may therefore take on exactly one value from the enumerator list The Chora compiler is very strict in handling enumeration data types and prevents the programmer from assigning to a variable of a particular enumeration type a value that has not been explicitly defined in the enumeration
125. e class contains graphical objects these objects are also drawn on the screen The attributes of the class can be set directly in the Inspector window when the appropriate class brick has been previously selected MainMenultem4 const string 17 D MainMenultem5 const string 18 Menu class Menu Menu 32 MenuCaption const string 36 sl Brick ca lala apene alae Description The class DemoMenu MainMenu im Generator false MultiLingual true SuperClass Menu Menu e SuperClass The class name of the super class This attribute refers to the ancestor of the class This attribute is optional and should be set for derived classes only Description bel 4 1 1 Instance variables Instance variables are always introduced with the keyword var followed by the data type the name and optional an initialization value of the variable Embedded Wizard Copyright TARA Systems GmbH Page 23 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class Item var int32 Counter var string Caption Video Settings In this example the definition of the Item class has been given two variables Counter and Caption The int32 data type of the Counter variable determines that the variable can store 32 bit signed integer values The second variable Caption on the other hand stores a string that is a sequence of characters A variable does not necessarily have to be initialized right when i
126. e control does not belong to the form f f Count all controls while view null if Forms Ctrljview null count count 1 4 1 5 1 Native methods Normally the logic of a method is defined in the Chora language and the Chora compiler is responsible for translating the logic into statements appropriate to the target system Unfortunately Chora does not permit direct access to the hardware or to the services of the operating system This limitation is however a reasonable one given that in the GUI developed in Chora aims for the greatest possible degree of platform independence If direct access to the hardware or operating system is nonetheless necessary it can be done within a native method in the language of the target system e g ANSI C The use of native methods allows a mixture of Chora and native code However it prevents platform independent GUI development In practice native methods should be used only in developing driver classes A driver class serves as an interface between the GUI and the underlying target system By adapting the driver class the GUI program can be ported to other target platforms The definition of a native method is specially signed using the keyword native During translation the Chora compiler ignores the logic of a native method and places it unchanged in the generated code Thus one is in a position to mix arbitrary C C or assembler code with Chora and to define a clea
127. e dependent constant must contain a value for the Default language Non language dependent constants are assigned a single value based on the Default language Please also note that the names of languages used in the definition must be defined in the project file In this case the project file must define the two languages German and Default The choice of the appropriate language dependent value of a constant happens at the runtime of the Chora program and is completely transparent to the programmer The programmer needs only to switch between the languages in order to set all constants to a value suitable to the language chosen More details in Language selection chapter 9 Optionally the const definition may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Soutput true const string Caption Hello World Embedded Wizard Copyright TARA Systems GmbH Page 55 Chora User Manual www embedded wizard de Unit file EWU TARA Systems For more details about the output directive see Control directives chapter 8 3 In Chora it is possible to override a constant by so called constant variants Constant variants provide a powerful technique for the extension and adaptation of constants Each time the constant is used Embedded Wizard determines automatically the appropriate variant and uses it instead gt
128. e given new values When the properties are re initialized the corresponding onset methods are automatically invoked so that the object can react to the change in properties Note that the name of the re initialized property must fit to one of the properties defined in the object s class If this is not the case the Chora compiler reports an error message An auto object does not necessarily have to contain re initialization values for its properties Often it suffices to use the property values defined in the object s class autobject System AudioController Audio In this case all properties of the object retain their original value No properties are re initialized The auto object can be accessed by its name in scope of the superior unit By using this full name the properties of the object can be read or modified and methods can be invoked TheUnit Audio Volume 100 TheUnit Audio DoSomething When an auto object is not in use anymore the Garbage Collector automatically disposes it The following access to the disposed object causes it to be instantiated and initialized again This is the major difference between auto objects and ordinary global objects which are known from other programming languages Within the Embedded Wizard IDE auto objects always appear as bricks in the Unit Composer window The attributes of the object can be set directly in the Inspector window when the appropriate object s brick has been
129. e property s onget and onset methods are circumvented and the property s value is read directly from memory or changed in memory as with a simple variable The above example demonstrates the use of the keyword pure within the onget and onset methods The onget method returns the value from the property s area of memory The onset method changes the content of this memory and forces a screen refresh It is not mandatory that the value of a property is placed in memory In many uses the onget and onset methods determine the property s value on request for example in the case of a property that returns the current time Storing the value would not make sense in such a case Further details on the definition and use of the onget and onset methods are found in onget methods chapter 4 1 5 2 onset methods chapter 4 1 5 3 and in Reference data types chapter 6 3 Because each object stores its own copy of its properties it is not possible to define global properties in Chora Changing a property of an object does not usually have any effect on the properties of other objects var Sample Item objectl new Sample Item var Sample Item object2 new Sample Item theObjectl1 Caption Sound Settings Thus if as the above example demonstrates the Caption property of object1 is changed at runtime this does not usually have an effect on the content of the second object object2 Its Caption prope
130. e way constants and resources are adapted Every constant and resource can be overridden by variants The colors bitmaps fonts menu strings etc used within the GUI application can then be substituted by new values In case of language dependent constants and resources new languages can be added All this is done without any modifications on the origin constant or resource gt see Constant Variants chapter 4 8 2 and Resource Variants chapter 4 8 3 The both concepts of multivariant and multilingual applications do complement one another Consequently a very powerful and unique technique is available where the appearance the behavior and the language dependent strings images colors etc can be defined and switched at the runtime The handling of multilingual applications is described more detailed in Language selection chapter 9 A variant does never exist alone it always belongs to the class constant or resource it has been derived from When the origin class constant or resource is used in the GUI application the Embedded Wizard will replace it with the appropriate variant automatically The following example demonstrates the definition of a variant MyCaption of the origin constant Menu Caption vconst MyCaption Menu Caption Hello variant Although the name of the variant MyCaption is well known it is not allowed to use it directly in an expression The constant can be accessed through its origin name Menu
131. econd initialization expression for the preset Color is not re evaluated because there are no language dependent constants or resource operands The Chora compiler analyses each initialization expression end generates the additional re initialization code only for expressions which contain at least one multilingual constant or resource operand The S multilingual directive affects the following class definition only If this directive is missing or it is set false no additional code for the automatic re initialization of this class members is generated The directive does not affect base or derived classes If necessary an initialization expressions may be excluded from the automatic re initialization To do this the expression have to start with the s percent minus init operator In this manner the following expression is ignored by the Chora compiler and will not be re initialized even if the expression is multilingual Embedded Wizard Copyright TARA Systems GmbH Page 176 Chora User Manual www embedded wizard de Language selection TARA Systems Smultilingual true class Menu public Core Group object Views Text Caption preset String TheUnit TheCaption In the same way the Chora compiler can be forced to generate re initialization code for a non multilingual expression In this case the s percent plus init operator have to be used Smultilingual true class Menu public Core Group object V
132. ect point or color instant properties allow direct access to the elements of the data type For example the value of the aloha component in a color operand can be queried or changed using the instant property alpha From the programmer s point of view instant properties are used like the properties of an object gt Index operator gt The index operator may be used only in conjunction with the instant data type string Using the index operator a character can be read from or written to a string gt Assignment operator gt Using the assignment operator the result of an expression is assigned to a variable or property 7 1 Unary instant operators A unary instant operator expects exactly one operand For example the unary minus operator can be used in an expression to change the sign of the operand var rect Bounds lt 10 24 68 128 gt var int32 Result Result Bounds x1 In this example the value of the Bounds x1 operand is computed and stored with a changed sign in the variable Result Embedded Wizard Copyright TARA Systems GmbH Page 121 Chora User Manual www embedded wizard de Operators TARA Systems If a unary operator is used on an expression this expression must be contained in parentheses var rect Bounds lt 10 24 68 128 gt var int32 Result Result Bounds x2 Bounds xl 1 If the parentheses are missing then the operator is applied only to the first operand with the consequ
133. elseif Sendif Serror Swarning Embedded Wizard Chora User Manual Copyright TARA Systems GmbH Page 166 www embedded wizard de Chora preprocessor TARA Systems You can read more about the preprocessor directives in Preprocessor directives chapter 8 2 8 2 Preprocessor directives The preprocessor directives allow the Chora compiler to exclude explicitly chunks of code from the code generation For example by evaluating a condition in the Sif directive the preprocessor decides whether the following chunk of code will pass the preprocessor or it will be ignored method void Mute if Splatform Tara Win32 RGBA8888 native _ send i2c Audio OFF Sendif Only if the condition Splatform Tara Win32 RGBA8888 is fulfilled the immediately following code lines up to the Sendif directive will pass the preprocessor If the condition is not fulfilled the Chora compiler ignores all these lines of code until the Sendif directive has been evaluated The if and Sendif directives may only be used by pairs That is to say each Sif directive must be closed by a endif directive Nesting of directives is not allowed and leads to a Chora error message if Splatform Tara Win32 RGBA8888 if Scomposer false Error Sendif if Scomposer true Error Sendif Sendif The preprocessor expects that the expression in the condition of a if directive will result in a value of either true or false Using
134. en by the enumerator list var Graphics AlignH align align Graphics AlignH Center Embedded Wizard Copyright TARA Systems GmbH Page 67 Chora User Manual www embedded wizard de Unit file EWU TARA Systems The above example demonstrates how a variable of the user defined enumeration data type Graphics AlignH is declared After the declaration the variable may contain one and only one element of this enumeration Other values are not allowed and are seen as errors by the Chora compiler as for example this attempt to combine two different enumerations in a single assignment var Graphics AlignH align align Sample OtherOptions DVD An enumeration data type is very practical if a variable may be given only one value from a limited list Any other values that are not listed may not be stored in the variable During the code generation Embedded Wizard converts automatically all affected enum definitions into code artifacts appropriate for the respective target system While this task the Code Generator assigns numeric values to the individual items of the generated enum definitions Usually this process starts with the value O for the first item 1 for the second 2 for the third and so far If desired the developer can control this automatic enumeration In this case it is possible to map Chora enum definitions to some corresponding definitions already existing in the target system In order to change the automatic e
135. ence that the entire expression produces a different in this case undesired result Chora supports the following unary operators Operator Operand Description name data type ints Unary plus The result is the unchanged value of the int16 rand int32 Opera uint8 J B Ee var float a 0 1369 uinea var float b 0 1251 float var float c c a c 0 1369 c b c 0 1251 ints Unary minus The result is the negative of the value int16 Bee of the operand The unary minus operator merely uints changes the sign of the operand If the operand is uint16 unsigned e g uint16 the operand is Doo automatically converted into a signed data type int16 int32 var float a 0 1369 var float b 0 12513 var float c c a c 0 1369 c b c 0 1251 ge ay Complement operator The result is the bitwise EC complement of the operand Each 0 bit in the e Ginks operand is set to 1 and each 1 bit in the operand is uintl6 set to 0 uint32 This operator can be applied only to integer data types in order to be able to modify these as bitfields var uint32 a OxAAAAAAAA var uint32 c Q sap Een 0x55555555 bool Logical negation The result is the logical negation of Embedded Wizard Copyright TARA Systems GmbH Page 122 Chora User Manual www embedded wizard de Operators TARA Systems the value of the operand false if the operand is true and true
136. ent either true or false If the argument is true the affected variant substitutes its origin class constant or resource permanently it is so called static variant In the following example the used Svariant directive forces the class Menu MenuItem to be substituted by its static variant AqualItem The class variant AqualItem substitutes its origin class Menu MenuItem Svariant true vclass AquaItem Menu MenulItem The Svariant directive accepts also profile and style names In this case the variant is used only if the specified profile or Copyright TARA Systems GmbH Page 171 www embedded wizard de Chora preprocessor TARA Systems Smultilingual Srect Embedded Wizard Chora User Manual style is currently selected The profiles can be selected during the code generation only This provides a more flexible kind of static variants which are resolved already during the code generation For example the following constant variant is used in the Win32 target system only Svariant Win32 vconst Caption Dialogs Caption Default Modified Caption The usage of style names in the variant directive provides dynamic variants The affected variant is used if the specified style is selected at the runtime only The Svariant directive accepts also a list of comma separated profile and style names In this case the variant condition is fulfilled if one of the specified profiles or styles
137. enu Thelcon AlphaName FileN ame ImageFile png FrameDelay FrameSize YariantCond The variant condition attribute This ee zem n oe la se sm Als se Die Description 4 8 4 Auto object Variants Auto object variants are always introduced by the keyword vautoobject followed by the name of the variant and the name of the origin auto object the ancestor vautoobject AudioLoud TheUnit Audio preset Volume 100 Using this definition we have created a variant AudioLoud of an auto object TheUnit Audio In the variant the initialization value of the Volume property has been modified This modification do affect the behavior of the origin auto object TheUnit Audio If at the runtime the origin auto object TheUnit Audio is accessed Embedded Wizard will automatically use AudioLoud object variant instead The developer does not need to take care about it var int32 theVolume TheUnit Audio Volume The Embedded Wizard performs the selection of the auto object variant automatically An explicit usage of an auto object variant is not allowed The following example will cause a Chora compiler error because TheUnit AudioLoud is an auto object variant instead of this the real auto object would be expected var int32 theVolume TheUnit AudioLoud Volume Embedded Wizard Copyright TARA Systems GmbH Page 79 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Option
138. er a set is empty or not An empty set does not enclose any enumerators Unit Align Top Left II var Unit Align a var Unit Align b var bool CF false true a isempty c b isempty c C C This instant property is read only You can t assign any values to isempty int32 array size The read access to the instant property size of an array returns the number of elements within this array gt the max capacity of the array array string a 4 array string b 4 2 var int32 c c a size IL e 4 c b size c 8 This instant property is read only You can t assign any values to size Table 7 6 When using instant properties it must be noted that not every instant property allows an assignment Thus for example it is not possible to use an assignment to modify the length of a string The instant property length is exclusively read only var string Text Hello World var int32 1 Text length 20 Error l Text length Ok Assignment to an instant property within the scope of a constant or a literal is also not allowed as neither the constant nor the literal can be changed In this case as well a Chora compiler error is reported Embedded Wizard Copyright TARA Systems GmbH Page 155 Chora User Manual www embedded wizard de Operators TARA Systems var point p lt 10 20 30 40 gt point2 lt 0 0 gt Error p lt 10 20 30 40 gt point2 Read access is Ok 7 10 In
139. erName 6 Ok c Hello 4 Ok c TheStringConstant 0 Ok Please note that the Chora string index operator should be used very carefully because it may lead to some side effects By using the Chora string index operator it is possible to encounter unexpected behavior in the software if you are modifying a string which effectively is a string constant In this case the modification is performed directly in the origin string constant and therefore it affects all parts of the software For example the following code does modify the constant string Embedded Wizard Copyright TARA Systems GmbH Page 157 Chora User Manual www embedded wizard de Operators TARA Systems NT ello World Hello World var string a var string b a 0O X a is Xello World trace b b is ALSO Xello World In such cases it is better to modify the strings by using the string instant methods remove and insert These methods do not have any side effects For more details see Instant methods chapter 7 8 7 11 Assignment operator The Chora assignment operator is used to store the result of an expression in variables properties or arrays The result is assigned to the variable var Sample Item Item new Sample Item var string Caption array rect Items 5 Caption Hello GetUserName Items 2 Item Bounds amp Clipping
140. eration gt Finally the preprocessor is concerned with evaluating the control directives These directives control the code generator and determine how the GUI application will appear in the Embedded Wizard composer editor For example the directive Soutput determines whether the class definition that immediately follows it should be passed on to the code generator or not Using output false the class can then be excluded from the code generation In general the Chora preprocessor works similar to the preprocessor familiar from C or C 8 1 Macro evaluation In order for the preprocessor to be able to recognize and replace a macro in the code of the GUI application the name of the macro must be introduced with a S dollar sign class Menu Core Group inherited property Bounds lt 0 0 Size gt Embedded Wizard Copyright TARA Systems GmbH Page 161 Chora User Manual www embedded wizard de Chora preprocessor TARA Systems This example demonstrates the use of the macro Size in the initialization of the property Bounds of a menu The Chora preprocessor recognizes from the leading sign that it is dealing with a macro and replaces the name of the macro including the GT sign with the macro s contents Assuming the macro contains the character string 640 480 then Bounds is initialized with the rectangle lt 0 0 640 480 gt In order for the preprocessor to be able to find and replace a macro each macro must a
141. ere may be no further characters before the line break The unit must have a unique name There may not be multiple units with the same name in a project file It is also not possible to use the same name for a unit as well as for a profile a language or a style Please note that each project must define at least one unit Within the Embedded Wizard IDE the units appear as bricks in the Project Composer window A double click on the unit brick will show its content The attributes of the unit can be set directly in the Inspector window when the appropriate unit brick has been previously selected le Core unit 3 CZ DemoDevice unit 2 P Menu unit 1 P DemoMenu unit bottom S Brick lt 10 110 150 150 gt Description The Demo Application Unit Directory A KA Splitted false Directory The path to the directory the unit ist stored in The path can be absolute e g CAN vOrnioct wl Inte i mr it ean ho rolativea Description 4 3 2 Profiles and macros A profile is always introduced using the keyword profile followed by the name of the profile itself profile Win32 Tara Win32 RGBA8888 Embedded Wizard Copyright TARA Systems GmbH Page 10 Chora User Manual www embedded wizard de Project file EWP TARA Systems Here a profile named Win32 is being defined This profile uses the Platform Package Tara Win32 RGBA8888 MS Windows in graphics mode RGBA 8 8 8 8 32 bits per pixel The Chora compiler will the
142. erties Properties are always introduced with the keyword property followed by the data type the name and optional an initialization value of the property Embedded Wizard Copyright TARA Systems GmbH Page 29 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class Item property int32 Counter property string Caption Video Settings In this example the definition of the Item class has been given two properties Counter and Caption The data type of the Counter property int32 specifies that the property can store 32 bit signed integer values The second property Caption on the other hand stores a string that is a sequence of characters A property does not necessarily have to be initialized right when it is defined In the example only the Caption property has been preassigned an initialization value namely Video Settings Thus if at runtime an object of the Item class is created the object s Caption property is automatically preassigned the character string Video Settings Properties that have not been explicitly given a value are assigned a default value of 0 zero A string property that has not been explicitly initialized if the initialization of Caption is missing would thus contain an empty string Chora defines a set of data types All of these data types may be used in defining a property A detailed description of the data types is found in Data types chapter 6 Access
143. ess a property of an object without necessarily knowing the identity of that object gt see Reference data types chapter 6 3 gt Simple and powerful infrastructure for registering of observers and delivering of notifications to them when the observed subject has been signaled This technique provides the basis for the Controller View model and is used in the development of complex GUI applications gt see attachobserver statement chapter 5 18 detachobserver statement chapter 5 19 and notifyobservers statement chapter 5 20 gt Auto objects which are instantiated automatically on request and released when they are not in use anymore Unlike the ordinary Chora objects auto objects do exist in the global scope so they can be directly accessed from anywhere of the Chora code Usually auto objects do serve as controller in the Controller View model and is used in the development of complex GUI applications gt see Auto objects chapter 4 4 gt A Chora preprocessor enables conditional code generation depending on the target system or profile chosen gt see Chora preprocessor chapter 8 and Profiles and macros chapter 3 2 gt Support for native methods and inline code In this way the platform independent Chora program code may be combined with the platform dependent native code of the target system gt see Native methods chapter 4 1 5 1 native statement chapter 5 17 and Inline code c
144. ess to the instant data types The programmer can use the instant methods to execute an operation on an instant data type He can for example search a string for a particular character using the instant method find var string text Hello world var int32 inx Search for the first occurrence of the character w inx text find w inx 6 From the programmer s point of view instant methods are used like the methods of an object with the distinction that instant methods are always used within the context of an instant data type Instant methods are a fixed part of the Chora programming language and can therefore not be changed The Chora programming language supports the following instant methods Instant method Description declaration string string left The left method extracts the first that is leftmost aCount characters from the string arg int32 aCount aString and returns a copy of the extracted substring If acount exceeds the string length then the entire string is returned If acount 0 the method returns an empty string mm var string sl Hello World var string s2 2 Hello Embedded Wizard Copyright TARA Systems GmbH Page 144 Chora User Manual www embedded wizard de Operators TARA Systems string string right arg int32 aCount string string middle arg int32 alIndex arg int32 aCount string string insert arg string aString arg int32
145. ete definition of the base class In this case for example the Rectangle Class inherits the Bounds and Color variables as well as the Draw method from the base class Sample Shape The Draw method was even overridden in order to allow the Rectangle class to do something that deviates from the generic Shape class If then at runtime the Draw method is called in the context of a Rectangle object the program automatically branches into the appropriate version of the method Embedded Wizard Copyright TARA Systems GmbH Page 21 Chora User Manual www embedded wizard de Unit file EWU TARA Systems The depth of the class inheritance is not limited by the Chora compiler Thus it is possible when using Chora to develop complex libraries of classes An example of this is the Mosaic library developed by TARA Systems which is delivered with the Embedded Wizard The empty class is worthy of special mention An empty class contains no members and is normally not derived from any other class Such classes are used exclusively as root classes in developing class libraries All classes or certain particular classes within the library may then be derived from this class in the usual manner The definition of an empty class is limited to the name of the class followed by a semicolon class GenericClass Normally the definition of a class assuming it is not an empty class consists of one or more members The following members may be def
146. eyEvent event Handle the user input switch event Code case Core KeyCode Exit ExitMenu case Core KeyCode Menu OpenMenu case Core KeyCode 0Ok SelectOk Otherwise the event remains unhandled default return null The event has been handled return this Depending on the result of the expression event Code the switch statement automatically branches into one of the case statements Each case statement defines a constant value for the purpose for example Core KeyCode Exit If the result of the event Code expression agrees with one of the constant values the appropriate case statement is executed No other statements are executed If for example the expression event Code gives the result Core KeyCode Menu the method OpenMenu will be called in the corresponding case statement The optional default statement is used when the result of an expression does not agree with any of the case statements In this case the switch statement branches into the default statement If the default statement is missing however no statements are executed in this case and the switch statement is left The absence of the default statement can in some cases lead to a logical runtime error if all of the possible results of the expression are not covered by suitable case statements To make the programmer aware of this possible source of error the absence of a default statement leads to a wa
147. f the GUI software developed and also reduces the size of the code Besides the object oriented paradigm the Chora programming language is distinguished by many other characteristics necessary in the development of GUI applications gt Objects no longer in use are destroyed automatically and memory used by them is automatically released thanks to the integrated Garbage Collector gt please refer to the chapter titled Garbage collection chapter 11 gt Support for resources such as bitmaps or fonts that are required in an GUI application gt please refer to the chapter titled Resources chapter 4 3 gt Support for the development of multilingual GUI applications A multilingual GUI application may contain text images etc for different languages gt please refer to the chapter titled Language selection chapter 9 gt Support for class constant and resource variants The variants allow the development of GUI applications whose appearance and behavior can be changed at the runtime This unique feature simplifies the implementation of skins themes target and resolution dependent GUls etc This feature also provides the customization of existing software in a way very transparent to the customer gt please refer to the chapter titled Variants chapter 4 8 and Usage of Variants chapter 10 gt A comprehensive set of supported data types from simple integer data types int8 int16 to complex data types
148. for more details see Variants chapter 4 8 Within the Embedded Wizard IDE the constants appear as bricks in the Unit Composer window The attributes of the constant can be set directly in the Inspector window when the appropriate constant s brick has been previously selected class Menu Menu LanguageMenu class Menu Menu 1 MainMenu class Menu Menu bott og MenuCaption const string 24 oF Brick lt 5 150 195 190 gt ConstantT ype string Description Generator false alues Main Menu Default Main Menu German Hauptmen Values Stores the default value of the constant Additional language dependent values of this constant are available after a click on sl Description bai 4 3 Resources Resources are always introduced with the keyword resource and the name of the resource itself resource Resources Bitmap Logo attr bitmapfile FileName logo png Embedded Wizard Copyright TARA Systems GmbH Page 56 Chora User Manual www embedded wizard de Unit file EWU TARA Systems resource Resources Font Digits attr fontname FontName Verdana attr fontquality Quality Low attr fontheight Height 24 attr fontranges Ranges Q 9 Here we have defined two resources with the names Logo and Digits The first resource contains a bitmap resource class Resource Bitmap From the definition of this resource the Chora com
149. ge 70 Chora User Manual www embedded wizard de Unit file EWU TARA Systems D Thirditem 55 Set set 2 D Seconditem item 1 Le Enum enum 1 gt D Firstltem item bottom Brick lt 280 70 430 110 gt Brick lt 160 10 300 50 gt Description This is a set defini Description Second item of th Generator fase Default 1034 Default Stores an optional initialization value for the enumerator item Embedded Wizard expects here an unsigned number e g sl Description bai Generator The code generation attribute determines how this selected member is handled by the Code Generator e D Description 4 8 Variants The programming language Chora provides a unique feature called variants This feature allows the development of GUI applications with multiple different appearances and behaviors The selection of the desired appearance and behavior is done during the code generation or at the runtime Depending on them we differentiate between static and dynamic variants The idea behind the variants is based on the object oriented concept of derivation This is realized in a way similar to the class inheritance the affected parts of the GUI can be simple derived and adapted The one big difference is that variants do override substitue the origin definitions they are derived from H at the runtime the definition is used Embedded Wizard does handle with the variant instead Following definitions can
150. ght TARA Systems GmbH Page 101 Chora User Manual www embedded wizard de Statements TARA Systems Note that the throw statement is suited only to fatal error situations Errors that may occur legally at runtime must be handled differently 5 15 trace debug statement The trace statement has the following syntax trace expression expression A trace statement expects one or more expressions that are evaluated when the statement is executed The results of these expressions are converted to text and output to the debugging console This makes it easier to search for bugs in a Chora program The following example demonstrates how the information on the view objects can be logged on every pass through the while loop var Core View theView Repeat while t until all views are evaluated theView null trace theView theView Visible theView Bounds Continue with the next view object theView theView next 5 16 tracestack debug statement The tracestack statement has the following syntax tracestack A tracestack statement does not expect any operands This statement outputs the names of the methods which are currently executing in the prototyping environment so it is easer to find out where a method has been called from Additionally the arguments and the local variables used within the methods are displayed Note this statement works in the prototyping environment of
151. gnal statement OnAction1 is moved to the end of the list of pending signals When executed the signals are delivered in the following order OnAction2 OnAction3 OnActionl Please note already delivered signals can t be posted again as long as the screen update is not performed In this case the postsignal statement fails and a runtime debug warning is displayed This limitation is important in order to avoid an endless delivery of signals The following example demonstrates it slot OnAction do something here The following statement fails because OnAction has already received the pending signal A debug warning will appear on the debug console postsignal OnAction Unlike the ordinary signal statement postsignal does not pass the sender of the signal to the affected slot method The hidden argument sender is always nu11 if the slot method is invoked due to a pending signal For more details see signal statement chapter 5 11 Unlike the idlesignal statement the delivery of posted pending signals is forced always before the screen update is performed For more details see idlesignal statement chapter 5 13 Please note that pending signals do affect the garbage collection As long as an object is waiting for a signal the object is still reachable and will not be reclaimed by the Garbage Collector For more details see Garbage collection chapter 11 Pending signals are very usef
152. guage selection TARA Systems An assignment to the variable language changes only the currently selected language This has no effect on constants or resources that have already been evaluated Changing languages has an effect only when constants or resources are re evaluated again var string textl var string text2 language Default textl Sample Caption language German text2 Sample Caption trace textl textl Hello World trace text2 text2 Hallo Welt The Chora compiler is able to generate the necessary re initialization code The language switch will then trigger the objects to re evaluate theirs language dependent initialization expressions and to redraw themselves This is done automatically in a way fully transparent to the programmer To use the automatic re initialization the class of affected objects should be signed as multilingual This is done by the Smultilingual directive multilingual true class Menu public Core Group object Views Text Caption preset String TheUnit TheCaption preset Color FFOOOOFF In this example all objects of the Menu class are able to reinitialize themselves Assumed the preset String was initialized with the value of a multilingual constant TheUnit TheCaption the affected initialization expression will be re evaluated automatically after the languages has changed The s
153. hapter 4 5 The Chora programming language with its GUI model forms the basis for the Embedded Wizard Embedded Wizard Copyright TARA Systems GmbH Page 6 Chora User Manual www embedded wizard de Programs in Chora TARA Systems 2 Programs in Chora A program in Chora can be developed using an ordinary text editor preferably one capable of syntax highlighting This simplifies the development of a program in Chora A Chora program consists of at least two files gt Project file gt Contains the description of the entire project Here the settings for the desired target platform are specified A project file controls the Chora compiler and can be compared to a make file A project file has the extension EWP gt Unit file gt Contains the actual definition of the GUI In the unit file the classes methods attributes and so forth are specified A unit file can be compared to a C or C file or to a Java package A unit file has the extension EWU A program in Chora may contain multiple unit files The unit files used must be listed in the project file so that the Chora compiler may use them during the translation The possibility of splitting a Chora program into multiple unit files also increases the reusability and maintainability of the software and further makes it possible for multiple programmers to work simultaneously on the same GUI To translate a Chora program to ANSI C the Chora compiler CHORAC EXE must be launc
154. hat this process is automatically controlled by the Runtime Environment so that the use of the super call super is superfluous and even undesirable The use of the optional keyword native allows the re constructors to be implemented in the form of native methods See also native statement chapter 5 17 For more details see Language selection chapter 9 4 2 Constants Constants are always introduced with the keyword const followed by the data type the name and value of the constant const string Caption Video Settings This defines a constant named Caption The constant s data type has been given as string whereby it is uniquely determined which values the constant may have In this case string means that the constant can store series of characters After the assignment operator there follows the actual value of the constant the string Video Settings Once defined constants may be used anywhere within the Chora program where constant expressions are allowed One can for example use a constant to initialize variables This ensures that the initial value of the variable is set in only one place even if there are multiple variables scattered throughout the Chora program Embedded Wizard Copyright TARA Systems GmbH Page 54 Chora User Manual www embedded wizard de Unit file EWU TARA Systems var string MyVariablel var string MyVariable2 MyVariablel Sample Caption MyVariable2 Sample
155. hed with the name of the desired project file For example chorac Elixir ewp Win32 The second argument Win32 defines the name of the desired profile A profile contains the definition of the target system In a project file multiple profiles may be contained each for a different target system When the Chora compiler is launched a profile must be selected explicitly in order to set the Chora compiler to the correct target platform If this is successful the Chora compiler creates a directory with the same name as the profile chosen and stores the automatically generated ANSI C files in this directory The names of the generated files are derived from the names of the unit files classes definitions etc If the Chora program can t successfully be translated all errors and warnings are reported so that the programmer may correct the cause of the error in the Chora program The more comfortable way to develop Chora programs is provided by the Embedded Wizard IDE Integrated Development Environment Embedded Wizard IDE provides a very effective environment for the development of GUI applications It is based on the idea of visual programming where software components so called bricks are arranged and connected with the mouse by simple drag amp drop From our point of view it was self evident to combine the visual programming and the GUI application development the both concepts complement one another The following f
156. hese properties In this way it is possible for one object to use a reference to read or write the property of another object without needing to know anything about the existence of that object A reference data type must always be derived from another existing data type The instant and user defined data types are suitable for this A reference data type is constructed using the prefix reference operator var string RefToString null var color RefToColor Menu BackgroundColor This example demonstrates how references of types string and color are defined The string reference RefToString is initialized with the value null This means that the reference is not yet linked to any property The color reference RefToColor on the other hand is initialized with a link to the property BackgroundColor of the object Menu Note the use of the reference operator to the left of Menu BackgroundColor This operator delivers a reference to the desired property In order to use the reference to access the contents of the property the reference must be dereferenced using the indirection operator Unlike the reference operator the indirection operator is placed to the right in the expression var color RefToColor Menu BackgroundColor var color NewColor 000000FF var color OldColor OldColor RefToColor read the referenced property RefToColor NewColor change the property Using the indirec
157. hod will be called so that the base class is notified of the change Embedded Wizard Copyright TARA Systems GmbH Page 32 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class Sounditem Sample Item Calls the base class version of the properties own onset method and passes Sound Settings inherited property Caption Sound Settings When a property is re initialized it is always the base version of the onset method that is invoked Even if the onset method has been explicitly overridden in the derived class the method version originally defined in the base class is the one invoked Only when the object s initialization is finished are the overridden methods activated Optionally the property definition may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Soutput true property string Caption Hello World For more details about the output directive see Control directives chapter 8 3 Within the Embedded Wizard IDE properties and their onset onget methods appear as bricks in the Class Composer window property string 8 onset y if onget D N Data E OnSetData i OnGetData l The attributes of the property and their onset onget method can be set directly in the Inspector window when the appropriate brick has been previously selected onget H
158. i Beside the language dependent constants and resources Chora also provides variants gt see Variants chapter 4 8 and Usage of Variants chapter 10 Embedded Wizard Chora User Manual Copyright TARA Systems GmbH www embedded wizard de Page 178 Usage of Variants TARA Systems 10 Usage of Variants Variants are a unique technique that was introduced into the Chora programming language in order to simplify the customization approach of existing Chora programs Using this feature the appearance and the behavior of an GUI application can be modified and extended without the necessity of any modifications on the existing software Within an GUI application multiple variants can be implemented and selected during the code generation or dynamically at the runtime This feature provides the basis for GUls with different appearances Skins and themes can be realized and the GUI can be adapted to target systems with different features and screen resolutions The variants are based on the concept of object oriented programming By deriving a variant from a class the implementation of the class can be adapted and extended as desired by the developer The methods of the class can be overridden the initialization values of inherited members can be changed and new members can be added to the class All these adaptations are possible without any modifications of the origin class gt see Class Variants chapter 4 8 1 In the sam
159. ied The effect of this attribute depends on the used Code Generator If the generator doesn t support the code obfuscation then the attribute has no effect on the generated code This attribute can take the values true or false only The value of this attribute may be evaluated in the Chora code using the build in macro obfuscation The size of the screen in pixel provided for this profile Embedded Wizard expects here a valid Chora point literal e g lt 720 576 gt The screen size determines the visible area of the entire GUI application To access the value of this attribute at the runtime the build in macro ScreenSize is available The name of the user defined application class The application class serves as the root of the GUI application Usually application classes are derived from the Mosaic class Core Root To access the value of this attribute at the runtime the build in macro SApplicationClass Is available The title of the GUI application as a string literal e g Solar Power Plant Control Panel The application title describes the GUI application The usage of this title depends on the target system For example in the Tara Win32 target the title is shown in the window caption To access the value of this attribute at the runtime the build in macro SApplicationTitle is available User defined optional application name as an identifier e g DashboardApp This attribute allows you to disti
160. iews Text Caption preset Color FFO000FF The order of the generated re initialization expressions corresponds to the Z order of the affected members This is the same order which is used to generate the first initialization code For more details see new operator chapter 7 6 Similar to the first initialization at the end of the re initialization the ReInit re constructor is invoked You can implement the ReInit method in order to do special re initializations which are not done by the automatic generated re initialization code Unlike the automatic re initialization the ReInit method is always invoked even if the affected class is signed as non multilingual For more details see Relnit re constructors chapter 4 1 5 7 In the Embedded Wizard IDE the value for the multilingual directive is defined directly in the Inspector Window Embedded Wizard Copyright TARA Systems GmbH Page 177 Chora User Manual www embedded wizard de Language selection TARA Systems Inspector E Search VideoMenu re Menu Menu LanguageMenu class Menu Menu i MainMenu class Menu Menu bott S Brick lt 160 10 310 50 gt Description The class DemoMenu MainMenu im Generator false MultiLingual true e SuperClass Menu Menu MultiLingual The multi lingual attribute determines whether objects of this class may react to the language switch and reinitialize themself automatically or not x Description e
161. igure shows the Embedded Wizard Main Window at work Embedded Wizard Copyright TARA Systems GmbH Page 7 Chora User Manual www embedded wizard de Programs in Chora TARA Systems C EmbeddedWizard Demo demo ewp Embedded Wizard loj xj i Navigation PaE Viet jee Edt Arrange Search Navigate Buld Debug Extras window Help i i or toolbars Z ss e bao 8 032 lean inn es s o T ntre iz mo Ce ZJilespkwcinms Zei ee ee Browser 5 FoR BD ffe MainMenu Inspector window Gallery window arg sting el Argument const string CD Constant Composer 1B em riet window V 113 xl Class Sheep Sheep Description Template for obj Generator false 100 null Mode Graphics Mode ne zi Bounds The property Bounds stores the position and the size of the group relative to owner of this group Log Resources Window Views Editor window P 4 slot DemoMenu MainMenuAction Var Menu Menu menu null 4 Which menu item has fired the signal E sender Iteml menu new E sender Item2 menu new DemoMenu Videom u Audi omen See es Item menu new DempMenu Ratingoenus sen DemoMenu MainMenu ItemS menu new DemoMenu HelpMenu Prototype the d ZE ege E Beie nels r akaa te ee H r Focus menu Statusbar 1 selected fe ni fe The software development with the Embedded
162. ill be used in order to substitute its origin definition Only if the condition is fulfilled the affected variant is applied In this manner multiple variants can be implemented and the user can switch between them The condition accepts a list of profile and style names The condition is fulfilled if one of the specified profiles or styles is selected The variant condition is evaluated as well as during the code generation and at the runtime H the condition is fulfilled already during the code generation the affected variant does substitute its origin definition permanently it can t be switched at the runtime anymore Such kind of a variant is called static variant Usually its condition depends on a profile which is then selected for the code generation The second kind is called dynamic variants Dynamic variants can be switched at the runtime if the appropriate variant condition depends on one of the active styles The activation and deactivation of styles is performed by assigning a set of style names to the global built in Chora variable styles For example the both styles AquaLook and WideScreen are activated in the following manner styles AquaLook WideScreen Alternatively the variant condition can be set to the literal true In this case the variant substitutes its origin definition permanently independent from any profiles or styles For more details about profiles and styles gt see Profiles and macros chapte
163. ill occur without a runtime error Without the if statement the danger exists that a method or property in the context of a null object will be used which invariably leads to a runtime error In addition the object cast operator may also be used with a null object In this case the object cast operator always returns null var Core View theView null if Sample Item theView null This condition will fail if Core View theView null And this condition will fail too When using the object cast operator it should be noted that this type conversion must occur dynamically at runtime With frequent use this can lead to a loss of performance We recommend using the object cast operator only in situations where the class of an object can t always be predicted at runtime In all other cases the Chora compiler takes care of statically verifying the variables classes methods etc in use Embedded Wizard Copyright TARA Systems GmbH Page 137 Chora User Manual www embedded wizard de Operators TARA Systems var Sample Item item new Sample Item No object cast necessary because item is already Sample Item item ItemCaption Setting The object cast operator functions in a way similar to the dynamic _cast lt gt operator familiar from the C programming language 7 5 enum and sert cast operators The enum or set cast operator is a special variant of the type conversion
164. imization level depends on the Code Generator of the selected Platform Package For example in case of the ANSI C Code Generator the order of the object s members is modified in order to compact small 8 16 bit variables together High The highest level of optimization forces an automatic elimination of unused variables methods classes constants resources etc This optimization level results in the smallest and fastest GUI applications This is because large parts of the Mosaic class library are designed as generic as possible If not used these parts are simply eliminated In this same way unused parts of your GUI application can be eliminated Tabelle 13 1 Depending on the set optimization level the Embedded Wizards analyses the dependencies between the members of the project It evaluates the logic of methods and determines which members are unused or can be accessed in a more effective way Then in the second pass the unused members are eliminated and the logic of the methods is adapted Embedded Wizard Copyright TARA Systems GmbH Page 190 Chora User Manual www embedded wizard de Optimization TARA Systems All these modifications are done during the code generation only and they do not affect the content of your project neither the eliminated variables are removed from your project nor the modifications done on the method s logic are taken over These optimizations are temporary while the code is generated only
165. in a very similar way A single attribute of a resource can then adopt a number of different values for example in order to define a bitmap resource Logo with two different images resource Resources Bitmap Logo attr bitmapfile FileName German GermanBanner png Default EnglishBanner png 1 Note the use of the Default language in the above definition By means of Default the language independent content of a constant or resource is set Any languages not explicitly listed in the definition will consequently use the content of Default Any multilingual constant or resource must define at least the Default language variant If Default is missing a Chora error is caused Further details on the definition of constants and resources are found in the chapters Constants chapter 4 2 and Resources chapter 4 3 Embedded Wizard Copyright TARA Systems GmbH Page 174 Chora User Manual www embedded wizard de Language selection TARA Systems When a multilingual constant or resource is accessed at runtime the currently selected language is evaluated This selected language determines which language variant of the desired constant or resource is returned For example when the German language is selected the constant Caption defined above returns the string Hallo Welt For all other languages Default French Greek the string Hello World is returned The currently selected language is controlled by the global bui
166. in32 RGBA8888 attr ApplicationClass Menu Application attr ScreenSize lt 800 600 gt attr Optimization High Defines whether the EPG is enabled or not macro EnableEPG true language German language Default Embedded Wizard Copyright TARA Systems GmbH Page 18 Chora User Manual www embedded wizard de Unit file EWU TARA Systems 4 Unit file EWU Each Chora program contains at least one unit file In the unit files the classes their methods and so on are defined Which unit files belong to a project is specified in the project file A unit file must always begin with version directive This directive informs the Chora compiler of the syntax used in the unit file and is intended for the future file extensions The directive is followed by a version number For example Sversion 5 0 If the Chora compiler does not recognize the version number given the translation is aborted with an error message Behind the version directive there follow the actual definitions These include gt Classes gt The definition of a class contains the description of all attributes and all methods that belong to a class Thanks to the class derivation a class has to define only the new or changed attributes or only the methods overridden No other attributes or methods that are taken over unchanged in the derived class need to be listed gt Constants gt A constant bears a nam
167. ined gt Instance variables gt A simple variable that stores a value during the lifetime of an object whereby each object contains its own copy of the variable An object s variables store the state of that object for example the color in which a shape is to be drawn on the screen Instance variables always belong to an object to an instance it is not possible to define global variables gt Instance arrays gt An array is a variable that can store more than one value The values within the array can be accessed by using an index gt Properties gt A property is an intelligent variable In a manner completely transparent to the programmer accessing a property invokes a special onget or onset method in which each property has its own methods The programmer may define the logic of these methods himself in order to react to the specific aspects of read or write access to the property For example the programmer can have the screen contents updated automatically whenever a property is changed gt Embedded objects gt Any object may embed other objects of a different class Each embedded object belongs to the superior object Each superior object contains a copy of all the objects embedded within it When an object is created at runtime all objects embedded within it are automatically created as well Beside embedded objects Chora also supports so called auto objects gt see Auto objects chapter 4 4 gt Methods gt
168. ing signal to a selected slot of an object The signal is delivered always after the screen update is performed and no user inputs are waiting for execution Unlike the ordinary signal statement idlesignal is suited for deferred code execution and for performing of idle tasks gt throw exception statement gt The throw statement causes an exception to be thrown The result is an immediate transfer of control to the error handler a global panic function within the Runtime Environment Exceptions are non recoverable errors that occur when executing a method If an exception is thrown at runtime the program can t be executed further gt trace debug statement gt The trace debug statement is only for test purposes The programmer can use this command to evaluate an expression at runtime and to send the result to the debug console gt tracestack debug statement gt The tracestack debug statement is only for test purposes in the prototyping environment of Embedded Wizard The programmer can use this command to evaluate the calling stack at runtime gt native statement gt The native statement allows the programmer to insert native code for example calls to C functions directly into the body of a method In this manner the Chora statements and the native statements can be mixed together within one and the same method The native statement is for the code generation only the Embedded Wizard is not able to interpret the enclosed
169. ings preset Background FF2020FF e SE In this example the definition of the Menu class has been given an embedded object named Item1 The embedded object is an instance of the class Sample Item The object s two properties Caption and Background are immediately initialized with new values This definition results in each Menu object having its own embedded Sample Item object The preset keywords force the properties of an object to be re initialized If a property is not explicitly re initialized using preset the property retains the value originally defined in the object s class Thus only properties that have been re initialized using preset are given new values When the properties are re initialized the corresponding onset methods are automatically invoked so that the object can react to the change in properties Note that the name of the re initialized property must fit to one of the properties defined in the object s class If this is not the case the Chora compiler reports an error message An embedded object does not necessarily have to be initialized at the time of definition Often it suffices to use the property values defined in the object s class class Menu object Sample Item Item1 Embedded Wizard Copyright TARA Systems GmbH Page 34 Chora User Manual www embedded wizard de Unit file EWU TARA Systems In this case all properties of the object retain their original value No properties a
170. int color color styles styles set set int P int float float char char Embedded Wizard Chora User Manual var rect a lt 10 20 30 40 gt var point b lt 5 7 gt var rect cC C a be 77 eS 315527 425 4 72 Point movement The result is the left point operand moved by the offset given in the right point operand The movement will be done in the positivie direction var point a lt 10 20 gt var point b lt 5 7 gt var point c c a b c lt 15 27 gt Color addition with saturation The addition will be done for each color component separately In the case the addition results in a value gt 255 the value will be adjusted automatically to 255 saturation var color a 10CO50FF var color b 225F22FF var color c c a b c 32FF72FF Union of two styles sets The result is a new styles set which contains the style names from the both operands var styles a Aqua var styles WideScreen var styles c O II c zs at b c Aqua WideScreen Union of two sets The result is a new set which contains the enumerators from the both operands var Unit Align a var Unit Align b var Unit Align c Unit Align Top Unit Align Right c atb c Unit Align Top Right Subtraction The result is the arithmetic difference of the operands var int32 a 1369 var int32 b 1251 var int32 c Copyright TARA Sy
171. ion value Video Settings In deriving classes all variables defined in the base class are automatically inherited by the new class The inherited variables do not have to be redefined unless the programmer wishes to change a variable s initialization value Then and only then the definition of an inherited variable can be given in the derived class and initialized using a different value class Sounditem Sample Item inherited var Caption Sound Settings Embedded Wizard Copyright TARA Systems GmbH Page 24 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Note the use of the keyword inherited Each inherited variable that is to be re initialized in the derived class must be introduced using the keyword inherited If this keyword is missing the Chora compiler will report an error message Moreover the data type of the variable in the derived class may not be specified Only the first definition of the variable expects the data type Inherited variables will inherit the data type from theirs ancestors A given variable s initialization value that is changed during derivation is valid only for objects of this derived class Objects of any of the base classes are not affected and their variables retain their original initialization values var Sample Item objectl new Sample Item var Sample SoundItem object2 new Sample SoundItem In this example the first object an object
172. irectives Embedded Wizard Copyright TARA Systems GmbH Page 65 Chora User Manual www embedded wizard de Unit file EWU TARA Systems inline DebuggerOutput if S platform Tara Win32 static void Debug char aMsg printf aMsg Selse static void Debug char aMsg __ error msg aMsg 0 Sendif By using the Sif else Selseif and S endif Chora preprocessor directives part of the code block depending on the target platform can be ignored or taken over If the condition in an if or Selseif directive is fulfilled is true the following part of the code block is taken over If the condition is not fulfilled the code block is ignored Details of the Chora preprocessor are found in Chora preprocessor chapter 8 The inline code blocks are placed in the generated ANSI C file according to their sequence Z order within the unit file together with other definitions such as classes constants resources and so on Optionally the inline definition may be prefixed with the Soutput directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Soutput true inline DebuggerOutput For more details about the output directive see Control directives chapter 8 3 Within the Embedded Wizard IDE the inline code blocks appear as bricks in the Unit Composer window The attributes of the inline code block
173. is operator The parentthis operator is used whenever an embedded object needs to access its superior object In this case the operator determines this superior object and returns it If the object has not been embedded parentthis will always return null This operator is very useful when an object needs to know whether it is embedded within a superior object or whether it has been created dynamically by the new operator if parentthis null this object is embedded within parentthis else this object has been created by the new operator For more details about the new operator see new operator chapter 7 6 7 13 classof operator The classof operator determines the class of an object The affected object expression must be given to the right of the classof operator var object anObject GetAnObject var class theClass classof anObject The operator returns a value of type class If the operator is applied on nu11 object the operator returns null class This operator is very useful when the class of an object should be determined and stored for further processing For example the returned class can be passed to the new operator in order to create an object of the given class var class theClass classof anObject var object theObject new theClass In order to verify whether the class is derived from a desired class the class cast operator may be used The class cast operator returns nu
174. is coordinate value and the write access changes it The other coordinate values are not affected var rect a lt 10 20 30 40 gt var int32 c Get the yl coordinate c a yl c 20 change the yl coordinate a yl 0 a lt 10 0 30 40 gt The instant property x2 corresponds to the X2 right coordinate of the rectangle The read access to this property returns this coordinate value and the write access changes it The other coordinate values are not affected var rect a lt 10 20 30 40 gt var int32 c Get the x2 coordinate c a XxX2 c 30 change the x2 coordinate a x2 100 a lt 10 20 100 40 gt Copyright TARA Systems GmbH Page 150 www embedded wizard de Operators TARA Systems int32 rect y2 The instant property y2 corresponds to the Y2 bottom coordinate of the rectangle The read access to this property returns this coordinate value and the write access changes it The other coordinate values are not affected var rect a lt 10 20 30 40 gt var int32 c Get the y2 coordinate c a y2 c 40 change the y2 coordinate a y2 100 a lt 10 20 30 100 gt int32 rect w The instant property w corresponds to the width of the rectangle The read access to this property returns the width and the write access changes it The width of the rectangle is calculated by subtracting the coordinates of the left border X1 from the right border X2 var rect a lt
175. is selected S variant Aqua Graphite vclass NiceItem Menu MenulItem If not explicitly specified the default value for this directive is set true For more details see Variants chapter 4 8 and Usage of Variants chapter 10 The multilingual directive controls the code generation for the automatic re initialization of class objects as a result of the language switch This directive affects the members of the following class definition only multilingual expects an argument either true or false Enable automatic re initialization Smultilingual true class Menu Core Group If not explicitly specified the default value for this directive is set false For more details see Language selection chapter 9 The rect directive defines the position and the size of a brick symbol of the definition that immediately follows These dimensions are used internally in the Embedded Wizard to arrange the brick symbols in the composer editor Srect expects a rectangle as a rect literal rect lt 10 10 160 50 gt property string Caption Copyright TARA Systems GmbH Page 172 www embedded wizard de Chora preprocessor TARA Systems Sreorder Sversion Sinclude Embedded Wizard Chora User Manual The Sreorder directive is used in the definition of classes to change the Z order of inherited and new class members The Z order plays an important part in the initialization of objects gt See
176. is therefore platform independent and can be ported to another system with a minimum of effort A limiting factor is the graphical performance of the embedded systems used Depending on the color depth and screen resolution supported by the target system it may be necessary to adapt the appearance of the GUI when porting to a new target system The structure and syntax of Chora are largely based on the programming languages C C and Java This closeness simplifies and shortens the time needed to familiarize oneself with Chora Still Chora is not C and it is not Java Many language constructs such as the pointers and pointer arithmetic popular with C and C programmers are deliberately not supported in Chora These restrictions serve foremost to limit possible sources of error and to enable development of a platform independent GUI Further these restrictions make it easier for non C C and Java programmers to become familiar with Chora As an object oriented programming language Chora supports the following important object oriented paradigms gt Attributes gt variables of an object in which the state of the object can be stored e g text color Attributes are often called fields gt see Instance variables chapter 4 1 1 and Instance arrays chapter 4 1 2 gt Methods gt functions of an object By calling a method the object can be accessed For example an object can be drawn on screen by calling its Draw meth
177. ition shown above fulfilled and the following chunk of code can pass This condition applies in equal measure to the strings Tara Win32 Index8 and Tara Win32 RGBA8888 etc The wildcards are very practical for flexibly comparing character strings For example when the major version number of the Chora compiler must be evaluated Sif Sversion 1 Chora Compiler Version 1 00 1 13 1 2 etc Sendif Two additional directives S else and Selseif simplify the conditional code generation Any chunks of code after the Selse directive are considered by the Chora compiler only if the corresponding i condition is not fulfilled Sif Splatform Tara Win32 RGBA8888 Pass this code if the condition is true only else Pass this code if the condition is false only Sendif The Selseif directive combines else and Sif so that multiple chunks of code may successively pass the preprocessor each under a different condition Embedded Wizard Copyright TARA Systems GmbH Page 169 Chora User Manual www embedded wizard de Chora preprocessor TARA Systems Sif Splatform Tara Win32 RGBA8888 Pass this code if the condition is true only Selseif Splatform Tara Win32 Index8 Pass this code if the second condition is true Selseif Splatform Tara Win32 RGBA4444 Pass this code if the third condition is true Selse Pass this code if all conditions are false Sendir Directives may o
178. izard de Operators TARA Systems var string text var int32 volume 54 text volume text 54 The same procedure can be used when a method is called Here the method s definition is familiar to the Chora compiler so that the arguments for the method call can also be subjected to an implicit type conversion In a type conversion the value of the operand is converted to the desired target data type This conversion can in some cases mean the loss of data precision or sign Therefore the Chora compiler issues a warning if an implicit automatic type conversion at runtime could have a possible side effects The following example demonstrates how the implicit type conversion of int32 into int8 leads to a loss of data since int8 may store only 8 bits of data and can t accommodate the value 300 var int32 132 300 var int8 18 var uint32 u32 i8 132 Warning data loss i8 44 u32 132 Warning sign loss u32 OxFFFFFED4 i32 18 Ok 7 4 Object cast operators The object cast operator is a special variant of the type conversion in which an object s class is dynamically verified at runtime and can be changed The object type conversion is limited only to the evaluation of the class and the inheritance hierarchy of the affected object The object itself will not be changed When an object cast operator is used the desired name of the target class must be given in parentheses before the object v
179. ject it is ignored and the affected variant is not generated A variant can also depend on several profiles If one of the profiles specified in the directive is selected for the code generation the variant does substitute the origin constant variant Win32 Win32_Debug vconst MyCaption Menu Caption Hello variant As long as a variant depends on profiles it still remains static the variant will be selected already during the code generation and it can t be switched at the runtime anymore Only dynamic variants can be switched at the runtime Dynamic variants do always depend on styles In order to select the variant the style specified in its variant condition must become active For example the following constant variant MyCaption will substitute its origin constant Menu Caption if the style Aqua will become active at the runtime S variant Aqua veonst MyCaption Menu Caption Hello variant Please note there is no differences in the syntax of the variant directive for static and dynamic variants In both cases the directive expects identifiers separated by comma signs The specified identifiers are evaluated during the code generation At this time point the Chora compiler distinguishes between profiles and styles this results in static or dynamic variants In the Embedded Wizard IDE the variant condition and the ancestor of the variant are defined directly in the Inspector Window Embedded Wizard Copyright
180. l www embedded wizard de Project file EWP TARA Systems A comment must always directly precede the definition to which it applies Comments are very useful to document the functionality of units languages profiles etc Embedded Wizard uses the content of comments to give you a short description of members which have been selected in the Composer window of the Embedded Wizard application This description appears below the Inspector window For more details see Embedded Wizard User Manual Additionally Embedded Wizard is able to generate a documentation file with the description of your project including the class hierarchy declaration of classes methods properties constants resources etc This automatic generated documentation file can then be used or distributed as software reference manual of your project Further details to comments and their syntax can be found in Comments chapter 12 3 6 Example The following example shall demonstrate the structure of a project file The project consists of 2 units of 1 profile and 2 languages Sversion 5 0 The unit Core contains base classes View Group Root and Timer unit Core attr Directory Mosaic This is the unit containing menus menu items etc unit Menu attr Directory The profile Win32 defines a profile for the MS Windows target with the given resolution of 800x600 pixels profile Win32 Tara W
181. lanquage 14 P Default language 13 Win32_Index profile 12 sl Brick lt 10 60 150 100 gt Description The default Language Generator truel v Generator The code generation attribute determines how this selected member is handled by the Code Generator Die Description 3 4 Styles A style is always introduced by the keyword style followed by the name of the style itself style Aqua This defines a style named Aqua The name of the style can now be used in the definition of a class constant or resource variant For this purpose the variants accept a variant condition directive which determines when the origin class constant or resource is substituted by the affected variant In this manner an GUI application may contain multiple style dependent appearance and behaviour More details can be found in Variants chapter 4 8 and Usage of Variants chapter 10 Optionally the style definition may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Soutput true style Aqua The Soutput directive of a style does also affect the dependent variants If such a variant does depend on disabled styles only the variant is ignored by the code generation For more details about the output directive see Control directives chapter 8 3 Within the Embedded Wizard IDE styles appear a
182. lass theClass Views Text var object theObject new theClass If the new operator is applied on a oul class no object is created and the operator returns null Embedded Wizard Copyright TARA Systems GmbH Page 140 Chora User Manual www embedded wizard de Operators TARA Systems 7 7 Instant constructors Instant constructors take the name of the corresponding data types and expect additional arguments that are dependent on the declaration of the constructor Instant constructors are a fixed part of the Chora programming language and as such can t be changed Use of an instant constructor is similar to the call of an ordinary method The instant constructor expects arguments that it then uses to compute a value The value thus computed is then returned and can be used in an expression For example the instant constructor rect takes the 4 delivered arguments x y x 100 y 100 and builds a rect value which it returns so that this value can be assigned to bounds var rect bounds bounds rect x y x 100 y 200 One could compare an instant constructor to a very powerful type conversion operator that combines multiple arguments and that can convert them to the desired data type The Chora programming language supports the following instant constructors Instant constructor declaration Description string string This constructor converts the given signed number aValue in a string and returns the arg
183. lected for the code generation In all other cases the variant is ignored Svariant Win32 vresource MyLogo Menu Logo The Svariant directive allows the definition of multivariant resources A single resource can be overridden by multiple variants Which variant is finally used is determined during the code generation and at the runtime In this case we distinguish between static and dynamic variants Static variants depend on profiles and dynamic variants on styles For more details about the variant directive see Control directives chapter 8 3 In Chora it is also possible to derive a resource variant from another resource variant This results in very powerful instrument for the development of multivariant GUI applications and it simplifies the customization of existing software Within the Embedded Wizard IDE resource variants appear as resource bricks extended by a small icon in the Unit Composer window The attributes of the variant can be set directly in the Inspector window when the appropriate variants brick has been previously selected Embedded Wizard Copyright TARA Systems GmbH Page 78 Chora User Manual www embedded wizard de Unit file EWU TARA Systems E3 Thelcon ariant s9 MenuYariant class DemoMenu M 33 om Menu class Menu Menu 32 Thelcon resource Resources B 31 sl Brick lt 450 220 590 260 gt Description ResourceClass Resources Bitmap VariantCond true e VariantOF DemoM
184. llowing inline documentation will be extended by a cross reference to the description of the class Core View Override the Draw method of the super class Core View in order to be able to fill the background with the blue color inherited method Draw Identifiers started with the at sign are recognized as potential class unit or project members Depending on the context the at sign is used in the class hierarchy the unit or the list of languages profiles and styles is seek for a member which name matches the given identifier For example the following inline documentation will be extended by a cross reference to the description of the method HandleEvent The method DoSomething is called from the method HandleEvent each time a key down event arrives method void DoSomething While seeking for the member with the given identifier the inheritance hierarchy of the affected class is evaluated till one of the base classes contains the description of the desired member If the desired member is not defined in any of the base classes the members of the superior unit are evaluated If this operation is failed too the list of languages profiles and styles is searched in order to find a member with the given name The at sign itself does not appear in the generated documentation To display a single at sign use a double at sign The minus sign at the begi
185. logical operators and parentheses complex conditions can be created The Chora preprocessor supports the following operators Operator Operand Description name data type l bool Logical negation The result is the logical negation of the value of the operand false if the operand is true and true if the operand is false Sif Sprofile Win32 Embedded Wizard Copyright TARA Systems GmbH Page 167 Chora User Manual www embedded wizard de Chora preprocessor TARA Systems Sendif amp amp bool amp amp bool Logical and The result is true if both operands are true Sif Scomposer amp amp Sprototyper Sendif bool bool Logical or The result is true if one of the operands is true STE Ver 0 Ver 1 Sendif Op1 Op2 Equal to This operator returns true if both operands Op1 and Op2 result in exactly the same character string Sif abc abc Ok pass the preprocessor Sendif Sif abc ABC will be ignored Sendif Opl Op2 Not equal to This operator returns true if the two operands Op1 and Op2 do not result in exactly the same character string Sif abc abc will be ignored Sendif Sif abc ABC Ok pass the preprocessor Sendif Tabelle 8 2 By using these operators a complex condition can be formulated which is fulfilled only when the partial conditions for example Sprofile Win32 and Scomposer true are also fulfilled Sif profile Win32 E
186. lready have been defined explicitly Macros are defined in profiles gt Each profile can or must even contain its own set of macro definitions whereby the content of the macros may differ from profile to profile Thus the macro Size could be defined in a second profile with the character string 1024 768 if the relevant target system allows a high screen resolution Target with a low screen resolution profile Targetl Tara Win32 RGBA8888 macro Size 640 480 Target with a high screen resolution profile Target2 Tara Win32 RGBA8888 macro Size 1024 768 To allow the preprocessor to access the macros defined in a profile the relevant profile must be selected explicitly for the code generation For example when the Chora compiler is invoked the name of the desired profile must be passed on to the compiler as the last parameter chorac testproject ewp Target2 Each time the preprocessor recognizes a macro it searches the currently selected profile for the corresponding macro definition gets the character string stored there and use it to replace the found macro occurrence In the case that the required macro definition could not be found in the currently selected profile the Chora compiler will report a warning How profiles and macros are defined is explained in the chapter Profiles and macros chapter 3 2 A major difference between the Chora preprocessor and the C C preprocessors is the limitation that
187. lt in variable language language is one of the few global variables in the Chora programming language To switch the language the name of the desired language must be assigned to this global Language variable if SwitchToGermanCondition language German if SwitchToGreekCondition language Greek The content of the language variable can of course also be evaluated in an expression for example in order to query the currently selected language Toggle between Default and German language if language German language Default if language Default language German During the development the language can be selected in a convenient way directly in the Language combo box of the Embedded Wizard IDE 4 CO win2 RGBA Detaut E DI gt 3 Wah aj German 3 a 5 Project Cc aeolian D MainMenu Aside from the global built in variable 1anguage there is also an instant data type of the same name language This data type is used whenever variables properties or arrays must be defined in order to store there the name of a language Store the currently selected language in the temporary variable var language tmp language switch to the Default language language Default Do something here Restore the previously selected language language tmp Embedded Wizard Copyright TARA Systems GmbH Page 175 Chora User Manual www embedded wizard de Lan
188. m object else or call the base class version of the slot method to handle signals from other objects super sender In addition a slot method can like any other method contain native code class Device slot native OnOpenTray if S profile Chassis1 OpenTray Sendif Note that in addition to the keyword slot there is an identically named instant data type called slot This data type exists to define variables in which the entry point of a slot method can be stored Embedded Wizard Copyright TARA Systems GmbH Page 48 Chora User Manual www embedded wizard de Unit file EWU TARA Systems var slot theSlot theObject OnAction send a signal to the slot stored in the variable theSlot signal theSlot The use of slot variables simplifies the insulation between the sender and receiver objects The sender object is no longer dependent on knowing the identity of the receiver object It simply sends a signal without having to worry about which object will be receiving that signal At runtime the programmer can initialize the variable with the entry point of another slot in this process the signals are sent to a different slot without the sender object being having to be notified Additionally the statement postsignal and idlesignal can be used to send a pending signal after a short delay Further details on signals can be found in signal statement chapter 5 11 postsignal statemen
189. m the base class are always initialized by a simple assignment of values The initialization value is copied directly into the memory area of the affected variable property or array This means that a property s onset method is never called when the property is initialized the first time gt The re initialization of inherited variables and arrays also occurs through a simple assignment of values The initialization value is copied directly into the memory area of the affected variable or array gt When re initializing inherited properties on the other hand the onset method of the affected property is called with the initialization value as its argument gt Once all variables properties arrays and embedded objects have been correctly initialized the user defined init constructor is called Here the programmer can define additional initialization steps that go beyond simple assignment of values Further details are found in the chapter Init constructors chapter 4 1 5 5 Thanks to the Garbage Collector the programmer need not be concerned with destroying unused objects The Garbage Collector recognizes which objects are no longer in use and automatically disposes of them Please refer to the chapter Garbage collection chapter 11 Additionally if instead of the class name a class expression is placed right to the new operator the expression is evaluated at the runtime and an object of the determined class is created var c
190. mbine two different sets in a single assignment var Sample States states states Sample OtherStates Enabled TopMost The variable may also contain an empty set In this case no elements of the set are listed the brackets are empty Embedded Wizard Copyright TARA Systems GmbH Page 69 Chora User Manual www embedded wizard de Unit file EWU TARA Systems states Sample States A set data type is very practical if a variable may be given a combination of particular values from a limited list No other values not contained in the list may be stored in the variable Special operators allow the programmer to perform operations on sets He can determine the intersection or combination of two sets for example Further details about operators may be found in Operators chapter 7 During the code generation Embedded Wizard converts automatically all affected set definitions into code artifacts appropriate for the respective target system While this task the Code Generator assigns numeric values to the individual items of the generated set definitions Usually this process starts with the value 1 for the first item 2 for the second 4 for the third 8 for the fourth and so far up to 32 items If desired the developer can control this automatic enumeration In this case it is possible to map Chora set definitions to some corresponding definitions already existing in the target system In order to change the automatic en
191. me error is reported Please note the verification while the number to enum or number to set conversion is limited to the prototyping environment only At the runtime in the target system the enum and set operands are already handled as pure numbers gt no type conversion and no verification are applied In this case the resulting values may become invalid Therefore we recommend always to test the code within the prototyping environment 7 6 new operator The new operator is used whenever a new object an instance of a particular class must be created at runtime of an GUI application The name of this desired class must be given to the right of the new operator var Core Group theGroup var Views Text theText Create a new instance of the Views Text class theText new Views Text Prepare this new object Set the font and text the object should display on the screen theText Bounds lt 0 0 100 32 gt theText Font Sample VerdanaFont theText String Hello World And display this object theGroup Add theText UI When executed the new operator causes the Runtime Environment to reserve an area of memory for the new object and to initialize this object Embedded Wizard Copyright TARA Systems GmbH Page 139 Chora User Manual www embedded wizard de Operators TARA Systems The initialization process is done according to the definition of the object s class This definition deter
192. meLevel of the object controller notifyobservers controller VolumeLevel As soon as the property has been triggered the attached slot methods will receive post signals automatically see postsignal statement chapter 5 12 Before observers may receive notifications the observers need to be registered This is done by the statement attachobserver see attachobserver statement chapter 5 18 The following example demonstrates how a slot method update is registered as an observer attachobserver update controller VolumeLevel If the observer is no more needed the statement detachobserver can be used After the following operation the slot method update is detached from the property it is not able to receive any notifications triggered for the VolumeLevel property detachobserver update controller VolumeLevel For more details about detachobserver see detachobserver statement chaper 5 19 If the expression specified in the notifyobservers statement results in a null value no observers are notified and the program execution is continued without any error messages var object theObject null notifyobservers theObject This should not be mixed with the third form of the notifyobservers statement where the null value is passed explicitly as the first operand of the statement This form of the statement is designed especially for the notification of global object and property independent o
193. members are contained in this class Once it is defined the class serves as a template for creating objects The programmer can at runtime create as many objects of a class as he likes call methods of the objects or directly access the objects attributes var Sample Shape theObject new Sample Shape theObject Draw The above example demonstrates how a new object of class Sample Shape is created Note that the complete name of a class requires the name of the unit in which the class was defined Thus the Shape class was defined in the Sample unit If the unit name is missing the Chora compiler will not be able to find the class After its creation the object can be accessed In the above example the Draw method of this object is called making the object for example appear on the screen What exactly happens when the method is called depends of course on how it is implemented A special quality of classes is the ability of one class to inherit its definition from another class In so doing the definition of the base class is taken over completely by the new class The inherited definition can then later be extended or changed without influencing the base class To derive from a class the name of the base class must be given explicitly in the definition class Rectangle Sample Shape inherited method Draw Here we can draw the rectangle Each inherited class thus takes on the compl
194. mines precisely which variables properties or arrays are initialized and with what values The Runtime Environment therefore has only to assign initial values to all the relevant variables properties and arrays For further details see Classes chapter 4 1 When an object is initialized the following must be noted gt The initialization process always starts with the object s oldest base class This ensures that all variables properties and arrays defined in a base class have been properly initialized before the initialization of the derived class may proceed gt In initialization the Runtime Environment only considers variables properties and arrays for which an initial value was given in the definition of the class All other variables properties and arrays that have not been explicitly initialized still keep a value of 0 zero or the value already derived from the base class gt The initialization order is predetermined by the Z order The Z order reflects the order in which variables properties and arrays are listed within the definition of a class It is possible to alter the initialization order by moving individual variables properties or arrays up or down within the definition of the class See control directive reorder chapter 8 3 gt If the definition of the class contains embedded objects these are also initialized fully according to the Z order gt Variables properties and arrays that are not inherited fro
195. n can adopt only one of two possible values true or false var bool ItIsTrue true var bool ItIsFalse false char A single character Each character occupies 16 bit in memory so it is possible to encode all known characters Use of the worldwide character encoding standard UNICODE is possible A character is always enclosed by a set of single quotes Characters that can t be entered directly from the keyboard can be expressed in hexadecimal notation by using the x escape sequence var char signl S var char sign2 xBC74 In this way one is able to enter individual characters of a foreign language such as Japanese without having to depend on that keyboard or input machine Please note that the x escape sequence always expects to be followed by 4 hexadecimal digits The following list shows the entire set of supported escape sequences Each sequence always starts with a backslash sign The Chora compiler will automatically replace each found escape sequence with the corresponding character code a 0x0007 BEL Alert b 0x0008 BS Backspace f Ox000C FF Formfeed n 0x000A LF Newline r 0x000D CR Carriage return t 0x0009 HT Horizontal tab v 0x000B VT Vertical tab Ox005C A Backslash SA 0x0027 Single quote Vi 0x0022 Double quote EL d Oxttitt Character in 4 hex digit notation 0 0x0000 Null Character For example to express the new line character the following escape sequence coul
196. n have to generate code for the Tara Win32 RGBA8888 platform assuming that the profile Win32 is specified when launching the compiler chorac Elixir ewp Win32 The primary function of the profile is to cover the code generation settings for the particular target system The Code Generator evaluates these settings in order to decide how to generate the code for this target system The settings are introduced by the attr keyword and listed within the braces block of the profile profile Win32 Tara Win32 RGBA8888 attr Optimization High attr Obfuscation false attr ScreenSize lt 640 480 gt attr Verbose false attr Clut defaultclut txt attr OutputDirectory c temp emwisrc attr PostProcess nmake f makefile mak attr ApplicationClass Example Application attr ApplicationTitle Hello World Example attr ApplicationName HelloWorld Attribute name Description Clut The name of the Color Lookup Table CLUT file containing the definition of colors used within this GUI application The CLUT is used for Index8 platforms only In all other cases the value of this attribute is simply ignored If no CLUT file is specified the default file DefaultClut txt is used To access the value of this attribute at the runtime the build in macro Clut is available Optimization The optimization level attribute controls the code generation Depending on the value of this attribute the Code
197. n to the slot method of the receiver object in a hidden argument sender Within the slot method the source of the signal can thus be determined Except for the identity of the sender a signal delivers no further data Signals exist only for the sake of notification that something has changed Additional details in slot methods chapter 4 1 5 4 Additionally the statement postsignal and idlesignal can be used to send a pending signal after a short delay Further details on pending signals are found in postsignal statement chapter 5 12 and idlesignal statement chapter 5 13 Embedded Wizard Copyright TARA Systems GmbH Page 97 Chora User Manual www embedded wizard de Statements TARA Systems 5 12 postsignal statement A postsignal statement records a pending signal to an object for a deferred delivery The signal is delivered immediately before the screen update is performed When the signal is delivered it is sent to a slot of an object using the corresponding slot method The postignal statement has the following syntax postsignal expression The expression in the postsignal statement must result in data type slot otherwise the Chora compiler will indicate an error The following example demonstrates the use of the postsignal statement to record a pending signal to the OnAction slot of the object theObject var slot theSlot theObject OnAction Record a signal to the OnAction slot of the theObject
198. nds into numbers and vice versa The following example demonstrates the conversion from a set to a uint32 operand var Sample States states var uint32 number states Sample States Visible Highlighted number uint32 states Embedded Wizard Copyright TARA Systems GmbH Page 138 Chora User Manual www embedded wizard de Operators TARA Systems The resulting value of the conversion depends on the appropriate set definition If not explicitly specified the items of a set definition are enumerated automatically starting with the value 1 for the first item 2 for the second 4 for the third and so far Assumed that within the Sample States definitions Visible is the first item and Highlighted is the third item the operator will result the value 1 4 5 For more details see Sets chapter 4 7 The following example demonstrates the conversion in the reverse direction In this case a number is converted into a set operand of the given type var Sample States states var uint32 number number 5 states Sample States number The idea of this cast operator is the same as the one of the number to enum type cast The operator evaluates at the runtime specified set definition and looks for items which will correspond to the given number If successful the operator returns the affected items as a set If the set definition does not contain any corresponding items the cast operator fails and a runti
199. new operator chapter 7 6 Sreorder allows to change the Z order of a member For this purpose Sreorder expects the name of the affected member and the desired displacement number S reorder Caption 2 The reorder can be placed anywhere inside the definition of a Class Generally it may be very confused to determine the correct Z order of a member defined and derived in several classes The Z order of a member is affected by other members defined in the base classes by the reorder directives For this purpose Sreorder directives are prepared automatically by Embedded Wizard after a class has been modified in the Composer window The Sversion directive must at the beginning of any project or unit determine the version of the Chora syntax used Sversion 5 0 If this directive is missing the Chora compiler assumes that the version of the used Chora syntax is 1 0 It is important to determine the correct version of the used syntax because of the modifications in syntax between the version 1 0 and 2 0 If this directive is used correctly the Chora compiler is able to evaluate files containing Chora 1 0 and 2 0 Mixing of files with different syntax versions is possible The include directive specifies an include file of a split unit This directive is valid within the DIR file only The include directive is followed by the name of the affected include file without the extension Sinclude Timer More details can be fo
200. ngle math_acos 0 5 angle 60 0 var float angle math_asin 0 5 angle 30 0 The function math _pow calculates value of aA power aB For example var float x 2 5 var float x2 math_pow x 2 0 x 6 25 var float x3 math_pow x 3 0 x 15 625 The function math _sqrt calculates the square root value of the given aValue For example it is used for vector length calculation var float vecX 10 5 var float vecY 4 6 var float len math_sqrt vecX vecX vecY vecY len 11 4634 The both functions math _rand return random values from the given range aValuel aValue2 The quality of the returned values depends on the random generator implementation available in the underlying target system Usually the typical solution will provide pseudo random numbers only Please note the existing limitation in the usage of the int32 version of math rand The function can return incorrect values in case of too large range specified in the aValuel and aValue2 parameters If using this int32 version please avoid ranges larger than 32767 Embedded Wizard Chora User Manual Copyright TARA Systems GmbH www embedded wizard de Page 160 Chora preprocessor TARA Systems 8 Chora preprocessor The Chora programming language allows the development of platform independent GUI applications In the most favorable case such an GUI application may be ported directly to a new platform In
201. nguish the application within an environment executing simultaneously multiple Embedded Wizard applications The effect of this attribute depends on the platform package Copyright TARA Systems GmbH Page 12 www embedded wizard de Project file EWP TARA Systems Verbose OutputDirectory OutputPrefix PostProcess Embedded Wizard Chora User Manual used for the code generation If the generator doesn t support the code obfuscation then the attribute has no effect on the generated code The value of this attribute can be accessed from Chora by using the build in macro ApplicationName The verbose attribute controls the amount of comments included into the generated code If this attribute is true the Code Generator generates more detailed comments If this attribute is set false only the most important comments are included The effect of this attribute depends on the used Code Generator To access the value of this attribute at the runtime the build in macro verbose is available The path to the destination directory where the generated files should be stored in The path can be absolute e g C temp emwisrc or it can reside relative to the directory of the project file e g output This attribute is optional If no value is specified the Embedded Wizard per default stores the generated files into a sub directory with the name of the appropriate profile This attribute specifies an optional prefix
202. nly be used at the beginning of a line of code Only one directive is allowed per line of code After the directive no further Chora statements may follow in the same line of code The following example shows what is not allowed if Debug trace Menu Visible endif This example causes a Chora compiler error The Chora preprocessor provides also two additional directives Serror and Swarning If evaluated these directives force the Chora compiler to report an error or a warning These directives expect a message text which is then displayed in the compiler output Sif SFAST amp amp SSMALL Serror Invalid configuration settings Sendif 8 3 Control directives The Chora programming language supports the following control directives Directive name Description Soutput Die Soutput directive determines whether the definition immediately following it is considered during the code generation or simply ignored The simplest version of the Soutput directive expects a single bool argument either true or false In the following example the both output directives force the code generation for the class and the variable Generate code for this Menu class Soutput true class Menu Core Group Soutput true var string Caption Sound Embedded Wizard Copyright TARA Systems GmbH Page 170 Chora User Manual www embedded wizard de Chora preprocessor TARA Systems Svariant Embedded Wizard Chora User
203. nning of a text line is automatically converted in an HTML list item Per default the list items will appear preceded with a big dot within the documentation file For example The method DoSomething does following create a new menu object initialize the menu object display the menu on the screen method void DoSomething Embedded Wizard Copyright TARA Systems GmbH Page 188 Chora User Manual www embedded wizard de Comments TARA Systems The style of the generated documentation file is affected by the HTML cascaded style sheet file stylesheet css This file is stored together with other template files in the directory lt EmbeddedWizard gt HtmlDoc You can adapt this file to your own preferences so the used fonts colors text indent borders etc can be changed But the structure of the generated documentation can t be modified it is fixed implemented in the Embedded Wizard application In the Embedded Wizard IDE the description of a member can be specified in its attribute Description within the Inspector window after the appropriate member has been selected Embedded Wizard Chora User Manual Brick Description Generator Native Description The description of this selected member Embeded Wizard takes over this description into the generated code Additionally the description will appear in this D a Description The responder for all Men
204. numeration it is necessary to assign a designated numeric value to the appropriate item In such case the Code Generator takes over the given number and uses it for the enumeration of all following items enum AlignH item Left item Center 10 tem Right H The above example demonstrates the explicitly designation of a numeric value to an item within an enum definition In this case the second item Center has become a value 10 This will force the Code Generator to use the specified value for all occurrences of the item within the generated code As mentioned above the Code Generator also uses the specified value for the enumeration of all following items Therefore the third item Right will receive the value 11 Optionally the enum definition may be prefixed with the Soutput directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled output true enum AlignH For more details about the output directive see Control directives chapter 8 3 Within the Embedded Wizard IDE the enum definitions and their item enumerator members appear as bricks in the Composer window Embedded Wizard Copyright TARA Systems GmbH Page 68 Chora User Manual www embedded wizard de Unit file EWU TARA Systems The attributes of these definitions can be set directly in the Inspector window when the appropriate brick has been previou
205. od gt see Methods chapter 4 1 5 gt Properties gt are intelligent attributes of an object Unlike normal attributes each property has an onget and an onset method Accessing the property invokes the appropriate onget or onset method in a way that is completely transparent to the programmer gt see Properties chapter 4 1 3 gt Encapsulation gt The value of a property can be accessed only via its onget or onset methods In this way the contents of the property are protected from access outside the object gt Class derivation gt The class of an object can be derived from another class taking on the attributes and methods of the base class In the derived class the attributes or methods taken on may be overridden and adapted gt see Classes chapter 4 1 Embedded Wizard Copyright TARA Systems GmbH Page 4 Chora User Manual www embedded wizard de Introduction TARA Systems gt Polymorphism gt All methods of a class are virtual This means that the method of an object suited for the invocation is determined only at the runtime From the perspective of the calling method an object can thus take varying behavior the object is polymorphic For example a Draw method used in scope of a text object draws its text on the screen By contrast the Draw method of a rectangle object draws a rectangle The use of the object oriented paradigm increases the reusability maintainability and platform independence o
206. of class Sample Item still contains the original initialization value for Caption Video Settings The second object on the other hand has been instance modified by the derived class Sample SoundItem In this case the object s Caption variable obtains the value Sound Settings Optionally the var definition may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Soutput true var string Caption Hello World For more details about the output directive see Control directives chapter 8 3 Within the Embedded Wizard IDE variables appear as bricks in the Class Composer window i var bool E Sg Q IsActivated EE The attributes of the variable can be set directly in the Inspector window when the appropriate variable brick has been previously selected Embedded Wizard Copyright TARA Systems GmbH Page 25 Chora User Manual www embedded wizard de Unit file EWU TARA Systems IsActivated var bool 122 wi ColorE ffect object Effects ColorEff 121 Sheep object Sheep Sheep 120 Action slot 119 sl Brick lt 330 280 470 320 gt Description Stores true if the animation i Generator false Type bool e Default true Type The type of the variable property or an array Embedded Wizard expects here a valid Ble Description 4 1 2 Instance arrays Instance
207. of the method is overridden Often however it makes sense for the overridden method in the derived class to handle only one specific case and to direct all other cases to the method s original implementation in the base class The HandleFocus method demonstrates this kind of use The method s original version was defined in the Sample Menu class The SubMenu class overrides only this method and extends it to include handling of the focus loss aObtain false In all other cases the original version of the method can be used The method is called using the super call super This technique prevents the logic of a method from being copied without reason The Chora programming language categorizes methods according to their area of use Embedded Wizard Copyright TARA Systems GmbH Page 39 Chora User Manual www embedded wizard de Unit file EWU TARA Systems gt native method gt Allows Chora code to be mixed with the code of the target system In the native method you can directly adopt C C assembler and other code See also native statement chapter 5 17 onget method gt A specialized method that is invoked whenever the value of a property in an expression is to be queried Each property has its own onget method The return value of the onget method yields the queried value of the property onset methods gt A specialized method that is automatically invoked whenever the value of a property in an expression is to be
208. ofile thus a macro is valid only when the corresponding profile has been specified when launching the Chora compiler Macros defined in other profiles are ignored gt Languages gt Defining languages determines the countries for which the GUI is localized The localization makes it possible to develop an GUI in German English Japanese and so on gt Styles gt The styles are used to identify different variants of the GUI application Such multivariant GUI application may change its appearance and behaviour at the runtime This feature provides a simple way for the development of GUI applications with different skins and themes 3 1 Units A unit is always introduced using the keyword unit followed by the name of the unit itself unit Core attr Directory Mosaic Embedded Wizard Copyright TARA Systems GmbH Page 9 Chora User Manual www embedded wizard de Project file EWP TARA Systems This defines a unit named Core The Chora compiler will attempt to read the unit file Core ewu in order to generate the ANSI C code from it In so doing the compiler uses the attribute Directory in order to find the directory that contains the Core ewu file In the example above the unit file is searched for in the directory Mosaic relative to the project directory where the project file itself is stored Note the semicolon behind the attribute Directory The semicolon closes the attribute Behind the semicolon th
209. ome to ProductName property string Version Ver string Version method object HandleEvent arg aEvent var Core KeyEvent keyEvent Core KeyEvent aEvent if keyEvent null Switch keyEvent KeyCode case MenuKey OpenMenu MenuSize case CloseKey CloseMenu default return null Except for the above mentioned limitation each macro is evaluated and replaced by the preprocessor without any exception even if a macro has been used within a string char rect point color etc literal var string text ProductName var rect bounds lt 0 0 Size gt var color bgColor Red Green BluefFF Embedded Wizard Copyright TARA Systems GmbH Page 163 Chora User Manual www embedded wizard de Chora preprocessor TARA Systems Because the macro placement occurs even within string and char literals and because the sign is used exclusively by the preprocessor the character itself must be indicated by a sequence of two S signs The preprocessor replaces each sequence of 2 SS signs with a single character without evaluating any macros in the process var string pricel 100 Error var string price2 100 Ok 100 A further limitation concerns the nesting of macros Unlike with the C C preprocessor Chora macros can t be nested The nesting of macros would mean that in the definition of a macro a different macro would be used
210. ontext of the object to which the method belongs If the method expects arguments the arguments must be enclosed by parentheses when they are passed on at the time the method is called var Sample Menu theObject new Sample Menu theObject HandleFocus true Thus the above example invokes the HandleFocus method in the context of the object theObject In accordance with the definition of the HandleFocus method this method expects exactly one bool argument In this case the method is invoked with the value true as argument Calling a method in the context of an object means that the members of the object are directly accessible from the method s logic Thus for example the value of the variable isFocused can be accessed directly from the method class Menu var bool isFocused false method void HandleFocus arg bool aObtain isFocused aObtain Do something to handle the focus change Please note that each object contains its own copy of all variables properties and arrays that belong to it Thus a method can access only those variables in the context of the object of which it has been invoked Variables of other objects can t be accessed directly This is the main difference between methods and the functions familiar from the C programming language If desired a method can also expect more than one argument separated by commas Each argument must begin with the keyword arg class Shape
211. operty and the logic of the HandleEvent method have been modified These modifications do affect the appearance and the behaviour of the origin class Menu MenulItem If at the runtime an object of the origin class Menu MenuItem is created Embedded Wizard will automatically use AquaItem class variant instead The developer does not need to take care about it var Menu MenuItem theObject new Menu MenulItem The Embedded Wizard performs the selection of the class variant automatically An explicit usage of a class variant is not allowed The following example will cause a Chora compiler error because MyMenu Aqualtem is a class variant to create an object a real class is expected var MyMenu AquaItem theObject new MyMenu AquaItem The approach of the implementation of a class variant does not differ from the one of a real class Derived members can be overridden and new members can be added in the same way as this is described in Classes chapter 4 1 Optionally the vclass definition may be prefixed with the Svariant directive This directive determines the condition when the variant is used in order to substitute its origin class the variant is used only if the condition of the directive is fulfilled For example the following variant is used if the Win32 profile is selected for the code generation In all other cases the variant is ignored Svariant Win32 vclass AquaItem Menu Menultem The
212. or not and generates the relevant initialization code in order to correctly initialize the objects of this class Constructors are used almost exclusively with driver classes that require direct access to the operating system and hardware In this case constructors ensure correct hardware initialization and access to the operating system while the object is being created Classes that do not require access to the hardware or the operating system should not define constructors Except for the above mentioned restrictions on the definition of a constructor there are no further differences between constructors and methods Thus constructors are inheritable in the derivation of classes and can be overridden in the derived classes class SuperTimer Core Timer inherited method Init Do some stuff here but DON T make super call super aArg It must merely be noted that the Runtime Environment automatically calls all of an object s constructors when an object is created This process begins with the object s oldest base class and continues during initialization along the hierarchy of inheritance It can be inferred from the above example of the SuperTimer class that SuperTimer was derived from Core Timer Thus before the Init method of the SuperTimer class is executed the Runtime Environment takes care of initializing the Core Timer class and calling its Init method Only after that is the constructor of
213. ora statements are properly translated into the corresponding target specific code In contrast to it all code blocks which are enclosed within a native statement will be taken over into the generated code without any evaluation or verification the Chora compiler is not able to detect any errors within the native code block Please note the usage of the braces to enclose the native code block These braces belong to the native statement and are not taken over into the generated code If the enclosed code block also contains braces it is very important to ensure that each opened brace is always balanced with a corresponding closed brace otherwise the end of the native statement can t be recognized by the Chora compiler To insert a unbalanced brace an optional backslash sign in front of the brace should be used native IE E asw printf A unbalanced brace M Embedded Wizard Copyright TARA Systems GmbH Page 103 Chora User Manual www embedded wizard de Statements TARA Systems The end of the native statement The native statement is available during the code generation only In the prototyping environment of the Embedded Wizard no native statements are tolerated the Chora interpreter is not able to execute the enclosed target specific code so an error is reported In order to distinguish between different target platforms and the prototyping environment it is necessary to use the Chora prepro
214. ource a Resources Bitmap object is created and loaded with the content of the resource automatically The object can then be accessed like any other Chora object To prevent the GUI program from loading the same resource several times the Runtime Environment stores all resource objects that have already been loaded in a global table called resource map The management of this resource map is a part of the Resource Manager The Resource Manager prevents one and the same resource from being loaded into memory more than once and thus ensures that resources that have already been loaded are shared within the Chora program Embedded Wizard Copyright TARA Systems GmbH Page 57 Chora User Manual www embedded wizard de Unit file EWU TARA Systems In the unit file the definition of a resource is only a directive to the Chora compiler to read a certain external file e g Logo png or a Verdana font and to convert it into the format of the target system The attributes necessary for this are introduced using the keyword attr Depending on the type of resource different attributes may be needed If attributes are missing or if they contain the wrong values the Chora compiler reports an error message Each attribute consists of 3 elements the meta name the name of the attribute and the value of the attribute The meta name and the name of the attribute are fixed for each resource class A resource can as with constants be language dependent
215. ove the variant MyLogo extends the attribute FileName of the origin resource by a new value for the language French and overrides the inherited default value from EnglishLogo png to MyOwnLogo png The value for the German language still keeps unchanged From the programmer s point of view the resource Logo contains now 3 languages Please note the language French is new added to the resource In this way the customer can customize existing resources and adapt them to new languages The choice of the suitable language dependent resource occurs automatically at the runtime of the Chora program and is completely transparent to the programmer The programmer needs only to switch between the languages in order to set all resources to the language selected More details in Language selection chapter 9 The concepts of language dependent and multivariant resources do complement one another gt see Usage of Variants chapter 10 Beside the few differences described above the approach of the definition of a resource variant does not differ from the one of a real resource as it is described in Resources chapter 4 3 Optionally the vresource definition may be prefixed with the variant directive This directive determines the condition when the variant is used in order to substitute its origin resource the variant is used only if the condition of the directive is fulfilled For example the following variant is used if the Win32 profile is se
216. piler gets the name of a bitmap file logo png reads this file converts it automatically to a format suitable for the target system and stores the result in the ANSI C code that is generated The second resource is approached in the same way The Chora compiler recognizes from the resource class Resources Font that it is dealing with a font here In this case the compiler attempts to read from the Verdana font all characters in the range 0 9 and to convert these in a 24 pixel height font So converted characters are stored in the generated ANSI C code The name of the resource class categorizes the resource as belonging to a certain class bitmap font audio file etc If a resource is needed at the runtime of a Chora program the Resource Manager creates an object of this resource class automatically and loads it with the content of the resource Through this object the resource may be used now It may for example be used for drawing operations or one may query certain properties of the resource for example the width or height of the bitmap var Resources Bitmap bitmap var int32 width var int32 height Get the resource object the resource is loaded here bitmap Sample Logo Query some attributes of the resource etc width bitmap Size w height bitmap Size h This example demonstrates how the resource named Logo defined within the unit named Sample is accessed In accessing this res
217. ppear as the statement body The empty statement satisfies the syntax requirement in cases that do not need a substantive statement body This example illustrates the empty statement Repeat until the Condition returns false while object Condition r 5 5 Compound statement A compound statement can combine other statements into a block These individual statements are enclosed by braces if menu Visible true iteml Visible true item2 Visible true item3 Visible true When multiple statements are assembled into a block this block appears as a single complex statement a compound statement Compound statements are used wherever the Chora syntax allows only a single statement yet the program must execute multiple instructions at once This applies foremost to the if while and for statements Additionally a compound statement defines a range of validity for all local variables and arrays defined within its block Outside the block these variables and arrays lose their validity and can t be used Note the local variable theView Embedded Wizard Copyright TARA Systems GmbH Page 89 Chora User Manual www embedded wizard de Statements TARA Systems array Core View views 10 var int32 counter for counter 9 counter gt 0 counter counter 1 var Core View theView views counter theView Bounds lt 0 0 100 200 gt theView Visible true
218. property or object The syntax for the attachobserver statement has three forms Form 1 attachobserver slot method object id Form 2 attachobserver slot method property reference id Form 3 attachobserver slot method null id Embedded Wizard Copyright TARA Systems GmbH Page 105 Chora User Manual www embedded wizard de Statements TARA Systems These three forms differ in the type of the affected source In the first case the slot method is attached as an observer which will receive notifications triggered for an object object In the second case the observer will receive notifications triggered for a property specified in the expression property reference The third form allows the registration of a global object and property independent observer attachobserver update controller VolumeLevel The example above demonstrate the usage of the statement to register the slot method update as an observer for notifications triggered for the property VolumeLevel of the object controller As soon as the property has been triggered the attached slot method will receive a post signal automatically see postsignal statement chapter 5 12 The notifications are triggered by the statement notifyobservers see notifyobservers statement chapter 5 20 For example to trigger the property from the above example the following statement is used notifyobservers controller VolumeLevel
219. r In the above example the Menu class has been given a property named Color as well as a corresponding onget method Note that the name of the property must correspond exactly to the definition of the onget method If this is not the case the Chora compiler will report an error message Unlike other methods onget doesn t expect the return data type nor the arguments list The Chora compiler will adopt the data type of the property as the return data type of the corresponding onget method automatically Each time the value of the Color property is queried the property s onget method is called automatically var Sample Menu theObject new Sample Menu var color theColor theColor theObject Color The onget method s returned value thus determines the value of the property evaluated in an expression In the above example the onget method gives the true value of the property by reading it directly from memory using the keyword pure Often the onget method contains specialized logic to determine the value of the queried property on request for example a property that must always return the current time when queried Except for the definition that uses the keyword onget an onget method is no different from a normal method All onget methods are automatically inherited in class derivation and may be overridden in the derived class class SubMenu Sample Menu inherited onget Color return
220. r 3 2 and Styles chapter 3 4 If the variant condition is set to the literal default the variant substitutes its origin definition only when no other variant is available Alternatively the variant condition can be set to the literal true In this case the variant substitutes its origin defintion permanently independent If the condition of a variant is never fulfilled no code is generated for the affected variant This automatic elimination reduces the memory footprint of Chora programs If two variants of the same origin definition depend on the same variant condition a Chora compiler error is reported because the Embedded Wizard is not able to distinguish between those both variants It is also possible to derived variants from other variants So complex variant hierarchy is possible For more details gt see Usage of Variants chapter 10 4 8 1 Class Variants Class variants are always introduced by the keyword vclass followed by the name of the variant and the name of the origin class the ancestor Embedded Wizard Copyright TARA Systems GmbH Page 72 Chora User Manual www embedded wizard de Unit file EWU TARA Systems vclass AquaItem Menu MenuItem inherited property color Color 0088FFFF inherited method HandleEvent Handle events for the item Using this definition we have created a variant AquaItem of a class Menu MenulItem In the variant the value of the Color pr
221. r a property reference In this case several independent groups of observers may exists all attached to one and the same object or property The determination of the affected group is performed on the basis of the optional id operand detachobserver update controller 1369 If the optional operand is missed the value 0 zero is assumed automatically Observers which have not been detached manually are discarded by the Garbage Collector automatically as soon one the affected objects do not exist anymore 5 20 notifyobservers statement The notifyobservers statement triggers the given property or object in order to notify all observers which have been previously attached to the affected property or object The syntax for the notifyobservers statement has three forms Form 1 Embedded Wizard Copyright TARA Systems GmbH Page 109 Chora User Manual www embedded wizard de Statements TARA Systems notifyobservers object id Form 2 notifyobservers property reference id Form 3 notifyobservers null id These three forms differ in the type of the affected source In the first case the statement triggers an object object In the second case the property specified in the expression property reference is triggered The third form allows the notification of global object and property independent observers The following example notifies all observers previously registered by the property Volu
222. r interface between the GUI application and the target class AudioDevice method native void Mute Sif Splatform Tara Win32 send i2c Audio OFF Sendif 7 Embedded Wizard Copyright TARA Systems GmbH Page 42 Chora User Manual www embedded wizard de Unit file EWU TARA Systems In this example a class AudioDevice has been defined with a native method Mute This method can like any other method be called directly in Chora The main difference between this and a normal method is that its logic was written in the language of the target system in this case ANSI C Thus the native method invokes a fictitious send_i2c function in order to for example turn off the loudspeaker in a television set A native method can like any other method expect arguments and deliver return values Within the logic of a native method it is even possible to access objects call other methods etc All of this happens naturally in the language of the corresponding target system and requires a knowledge of the internal functioning of Chora objects and the Runtime Environment We recommend examining the code generated by the Chora compiler if you wish to write complex native methods In order to differentiate between different target platforms within a native method definition it is necessary to use the Chora preprocessor directives class AudioDevice method native void Mute if Sprofile Chassisl
223. r string Text2 world var string Result Result Textl Text2 A detailed description of the operators can be found in Operators chapter 7 6 2 User defined data types User defined data types are restricted to classes enumerations and sets The programmer uses these data types in definitions of variables properties arrays etc In the case of classes objects of the relevant class can be created The user defined data types are hardly different from the instant data types The only thing the programmer needs to bear in mind is using the full name of a user defined data type The name of the unit must always be included and separated by a double colon from the name of the class enumeration or set Embedded Wizard Copyright TARA Systems GmbH Page 117 Chora User Manual www embedded wizard de Data types TARA Systems var Sample Item Iteml new Sample Item Iteml Caption Sound Settings This example demonstrates how an object of the class Sample Item is created and how its property Caption obtains a value Note that the name of the class is used in conjunction with the name of the unit Sample where the class has been defined More about the definition of classes enumerations and sets can be found in Classes chapter 4 1 Enumerations chapter 4 6 and Sets chapter 4 7 6 3 Reference data types References allow the building of links to object s properties in order to access t
224. r the evaluation of complex expressions Priority Operator name highest unary f 2 e lt lt gt gt Embedded Wizard Copyright TARA Systems GmbH Page 132 Chora User Manual www embedded wizard de Operators TARA Systems amp amp lowest Table 7 3 This means that in an expression all unary operators are evaluated first followed by the and operators Partial expressions that use a logic or operator are on the other hand always evaluated last This order can be changed explicitly by the programmer through the use of parentheses As mentioned above an expression in parentheses is always evaluated first var int32 Resultl var int32 Result2 Resultl 123 456 789 Result2 123 456 789 This example demonstrates how the order of evaluation of an expression is influenced by the precedence of operators The first expression without parentheses contains two operators of differing priority and In this case the operator is evaluated first on the basis of its higher priority and the result of this partial expression is added to 123 In the second expression the parentheses force the partial expression with the operator to be evaluated before the operator After the operation Result1 has a value of 359907 Result2 on the other hand is initialized with a value of 456831 7 3 Instant cast operators Instant cast operators are used whenever an operand in
225. r uint8 g 0x34 var uint8 b 0x56 var uint8 a 0x78 bgColor 12345678 bgColor color r g b a This constructor does not expect an argument It returns merely a transparent color var color bgColor bgcolor 00000000 bgColor color This constructor initializes a new rectangle with the given aX1 ail aX2 aY2 coordinates and returns the initialized rect Var rect r var int32 x1 10 var int32 yl 20 var int32 x2 307 var int32 y2 40 r lt 10 20 30 40 gt r rect x1 yl x2 y2 This constructor initializes a new rectangle with the given points aPoint1 and aPoint2 and returns the initialized rect var rect Es var point pl lt 10 20 gt var point p2 lt 30 40 gt r lt 10 20 30 40 gt r rect pl p2 This constructor does not expect an argument It returns merely an empty rectangle var rect r ZZ ft DE 0 gt r rect This constructor initializes a new point with the given aX and ay values and returns the initialized point var point p var int32 x 10 Copyright TARA Systems GmbH Page 143 www embedded wizard de Operators TARA Systems var int32 y 20 p lt 10 20 gt p point x y point point This constructor does not expect an argument It returns merely a null point var point p p lt 0 0 gt p point Table 7 4 7 8 Instant methods Instant methods simplify acc
226. ra programming language and can therefore not be changed The Chora programming language supports the following instant properties Instant property declaration Description char char upper The read access to the instant property upper of a character returns its uppercase copy The original character will be unchanged var char a a var char b A var char c c a upper c A c b upper c A This instant property is read only You can t assign any values to upper char char lower The read access to the instant property lower of a character returns its lowercase copy The original Embedded Wizard Copyright TARA Systems GmbH Page 147 Chora User Manual www embedded wizard de Operators TARA Systems string string upper string string lower int32 string length uint8 color red Embedded Wizard Chora User Manual character will be unchanged var char a a var char b A var char c c a lower c ta c b lower ff Tat This instant property is read only You can t assign any values to lower The read access to the instant property upper of a string returns its uppercase copy The original string will be unchanged var string a Hello var string c c a upper c HELLO This instant property is read only You can t assign any values to upper The read access to the instant property lower ofa string returns its lowercase copy The origin
227. re Timer If an object of class SuperTimer is destroyed at runtime the SuperTimer Done method is executed first Only after that is the inherited version of the method from the base class Core Timer called Please note that this process is automatically controlled by the Runtime Environment so that use of the super call super is superfluous and even undesirable Use of the optional keyword native allows destructors to be implemented in the form of native methods Because destructors are intended primarily for direct access to the hardware and operating system most destructors will therefore be native methods See also native statement chapter 5 17 For more details see Garbage collection chapter 11 4 1 5 7 Relnit re constructors The definition of a re constructor is similar to an ordinary method A re constructor always has the name ReInit expects no arguments and may not return a value class MenuItem method void ReInit Caption GetCaptionForCurrentLanguage The re constructors are automatically invoked by the Chora Runtime Environment when the currently selected language changes to give the object the chance to request additional language dependent resources etc It is not necessary and in fact unadvisable to call the re constructors directly from the Chora code This can lead to inexplicable runtime errors var Menu MenulItem item new Menu Menultem DON T call re const
228. re is supported together with the new Graphics Engine 2 0 only If the file name contains a relative path the bitmap file will be Copyright TARA Systems GmbH Page 59 www embedded wizard de Unit file EWU TARA Systems FrameSize FrameDelay looked for relative to the directory of the unit file wnere the bitmap resource is defined This optional attribute is useful in case of a bitmap which consists of several small images frames Multi frame bitmaps can serve as image lists or they can contain short animation sequences Within the origin bitmap the frames are arranged in tiles side by side This attribute specifies the size in pixel of a single frame If you design multi frame bitmaps you can arrange the frames within the bitmap in rows and or in columns If this attribute is omitted the entire content of the bitmap is assumed as the only one frame In this case FrameSize is set automatically to the size of the origin bitmap This optional attribute is useful in case of a bitmap which contains an animation sequence To achieve this ensure first that the valid size of a single animation frame is specified in the FrameSize attribute FrameDelay specifies the delay in milliseconds between two animation frames In this manner the animation speed and the sequence of animation frames are stored together within a single bitmap resource If this attribute is omitted FrameDelay is set to 0 so the content of the bi
229. re re initialized The embedded object can be accessed by using its name in order to change the value of one of its properties for example or by using one of its methods var Sample Menu theObject new Sample Menu theObject Item1 Caption Sound Settings theObject Iteml1 DoSomething When classes are derived all objects defined in the base class are automatically inherited by the new class The inherited objects do not have to be redefined unless the programmer wishes to change the initialization value of the one of the properties of the inherited objects Then and only then the definition of the inherited objects in the derived class can be restated and initialized using a different value class SoundMenu Sample Menu inherited object Iteml preset Caption Sound Settings Note the use of the keyword inherited Any inherited object that is to be re initialized in the derived class must be introduced using the keyword inherited If this keyword is missing the Chora compiler will give an error message Moreover the class name of the object in the derived class may not be specified Only the first definition of the object expects the class name Inherited objects will inherit the class name from theirs ancestors An embedded object s initialization value changed in the derivation is valid only for objects of this derived class Objects of one of the base classes are not affected by the change an
230. rl 1 wipeE ffect class Core Timer bott Brick lt 0 100 200 140 gt Description This is a font resource Generator false ResourceClass Resources Fonnt FontName verdana v Height 32 Quality High Ranges Ox1F OxFF FontName The name of a TrueType font The desired font must exist and already be installed under Windows Only TrueType fonts are Ble Description 4 4 Auto objects Auto objects are introduced by the keyword autobject followed by the objects class the name and an optional a set of initialization values presets of the object Auto objects can only be defined in scope of a unit Embedded Wizard Copyright TARA Systems GmbH Page 63 Chora User Manual www embedded wizard de Unit file EWU TARA Systems autobject System AudioController Audio preset Volume preset Stereo 50 true In this example the definition of the unit contains an auto object named Audio The auto object is an instance of the class System AudioController The object s two properties Volume and Stereo should be initialized with the value 50 and true As soon as the auto object is accessed the first time it is instantiated The preset keywords force the properties of the object to be re initialized If a property is not explicitly re initialized using preset the property retains the value originally defined in the object s class Thus only properties that have been re initialized using preset ar
231. rning from the Chora compiler Please note that the expression in a switch statement and the constants in the dependent case statements must always be of the same data type A combination of various data types is not allowed and leads to a syntax error from the Chora compiler var char theChar switch theChar case A n EERS case B 2 uai case false Error Combination of char and bool data types default Embedded Wizard Copyright TARA Systems GmbH Page 92 Chora User Manual www embedded wizard de Statements TARA Systems Even the choice of allowed data types is limited to only the following bool char int8 int16 int32 uint8 uint16 uint32 user defined enumeration and language No other data types may be used in the switch statement nor in the case statements The following attempt to use the data type string meets with an error message from the Chora compiler switch CaptionText case Hello Error string datatype is case Hallo was not Supported by the switch statement default Despite the similarity in the C C and Java programming languages the Chora version of the switch statement has its own peculiarity the case and default statements do not have to end with a break The switch statement in C C and Java depends on the break statement to mark the end of a case or default statement If the break is mi
232. roperties etc can be signed with Soutput false in order to reach the best possible elimination results Usually it is enough that the application class itself is forced to generate the code All other members are invited automatically due to the existing dependencies from the application class The application class is usually derived from the Mosaic class Core Root For more details about the Optimization attribute and the Soutput directive see Profiles and macros chapter 3 2 and Control directives chapter 8 3 In the Embedded Wizard IDE the Optimization attribute can be set in the Inspector window after the appropriate profile brick has been selected The output directive is available for all unit and class members in the Inspector window as the Generator attribute Embedded Wizard Copyright TARA Systems GmbH Page 191 Chora User Manual www embedded wizard de Optimization TARA Systems Inspector E Inspector E Search Search profile ColorEffect object Effects ColorE ffect 121 CO Forms unit ais Sheep object Sheep Sheep 120 CO Effects unit 8 aAction slot 119 m Sheep unit 7v Item5 object Menu Menultem 118 x Brick lt 10 10 150 50 gt a Brick lt 340 130 480 170 gt Description Win32 test platform with 32 bit c Description The responder for all Menu Item sig Clut Generator false Optimization Highl 7 Native false OutputDirectory OutputPretix PlatformPackage Tara Win32 R
233. rror message they are simply ignored The Chora compiler recognizes whether or not a class has defined a destructor and generates the appropriate code to correctly deinitialize the objects of this class Destructors are used almost exclusively in driver classes that require direct access to the operating system and hardware In this case destructors take care of correctly deinitializing the hardware and maintaining access to the operating system during destruction of an object Classes that do not require access to the hardware or operating system should not define destructors Embedded Wizard Copyright TARA Systems GmbH Page 52 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Except for the above mentioned restrictions in defining a destructor there are no further differences between destructors and other methods Thus destructors may be inherited when deriving classes and may be overridden in the derived classes class SuperTimer Core Timer inherited method Done Do some stuff here but DON T make a super call super FE It must be noted that destructors are called only by the Chora Runtime Environment This process begins with the object s most recently derived class and continues during deinitialization along the hierarchy of inheritance until the oldest base class is reached It can be inferred from the above example of the SuperTimer class that SuperTimer was derived from Co
234. rsion of the onset Method super value After the value has been stored in the base class version of the onset method force an update of the screen etc UpdateAll In addition an onset method may contain native code just as with any other method class Time property int32 Seconds 0 onset native Seconds if Splatform Tara Win32 setclock value Sendif Embedded Wizard Copyright TARA Systems GmbH Page 46 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Further details on properties are found in Properties chapter 4 1 3 and Reference data types chapter 6 3 4 1 5 4 slot methods slot Methods are always introduced with the keyword slot followed by the slots name and the logic the body of the method class Menu slot OnAction Do something in response to the signal In the above example the Menu class has been given a slot method OnAction Note that a slot method defines neither arguments nor return data types Only the name of the slot method is specified When referring to the handling of signals a slot method is known simply as a slot The logic of the slot method is automatically executed whenever a signal arrives at the slot The process of sending a signal occurs through the use of the signal statement The following example demonstrates how a sender object sends a signal to the OnAction slot of object theObject v
235. rty still contains the original initialization value Video Settings provided that the property s onget and onset methods are not dependent on each other The programmer can namely query values of other objects using the onget methods and change other properties variables or objects using onset methods Thus simple access to a property can have an affect on other variables properties or objects Embedded Wizard Copyright TARA Systems GmbH Page 31 Chora User Manual www embedded wizard de Unit file EWU TARA Systems When classes are derived all properties defined in the base class including their onget and onset methods are automatically inherited by the new class The inherited properties do not have to be redefined unless the programmer wishes to change the initialization value of a property Then and only then the definition of the inherited property can be restated in the derived class and initialized using a different value class Sounditem Sample Item inherited property Caption Sound Settings Note the use of the keyword inherited Any inherited property that is to be re initialized in the derived class must be introduced using the keyword inherited If this keyword is missing the Chora compiler will give an error message Moreover the data type of the property in the derived class may not be specified Only the first definition of the property expects the data type Inherited properties will inherit the
236. ructors directly timer ReInit Embedded Wizard Copyright TARA Systems GmbH Page 53 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Since re constructors are optional the absence of re constructors does not lead to an error message they are simply ignored The Chora compiler recognizes whether a class has defined a re constructor or not and generates the relevant re initialization code in order to re initialize objects of this class correctly There are no differences between re constructors and methods Thus re constructors are inheritable in the derivation of classes and can be overridden in the derived classes class SuperMenulItem Menu MenuItem inherited method ReInit Do some stuff here but DON T make super call super It must merely be noted that the Runtime Environment automatically calls all of an object s re constructors when an object is re initialized This process begins with the object s oldest base class and continues during re initialization along the hierarchy of inheritance It can be inferred from the above example of the SuperMenulItem class that SuperMenulItem was derived from Menu MenulItem Thus before the ReInit method of the SuperMenuItem Class is executed the Runtime Environment takes care of re initializing the Menu MenuItem Class and calling its ReInit method Only after that is the re constructor of SuperMenuItem called Please note t
237. s Embedded Wizard Copyright TARA Systems GmbH Page 28 Chora User Manual www embedded wizard de Unit file EWU TARA Systems var Sample Menu object3 new Sample Menu Object3 Field 0 2 1369 If possible omit the usage of multi dimensional arrays because of possible changes in the future implementation of Chora The current implementation of arrays will be then replaced in order to support dynamic and open arrays Optionally the array definition may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Soutput true array bool Field 5 For more details about the output directive see Control directives chapter 8 3 Within the Embedded Wizard IDE arrays appear as bricks in the Class Composer window The attributes of the array can be set directly in the Inspector window when the appropriate array brick has been previously selected E AnimationSteps array point IsActivated var bool 122 wl Colort ffect object Effects ColorE ff 121 Sheep object Sheep Sheep 120 ha Description This is an array 4 Dimension 4 Generator false Type point EI Items 2 of 4 items 0 lt 100 120 gt 1 lt 110 120 gt sl 0 Stores the content of the array item This value is used to initialize the array during the creation of an object of this class Description bai 4 1 3 Prop
238. s GmbH Page 82 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Sversion 5 0 The Iconl bitmap contains a picture of a small speaker resource Resources Bitmap Iconl attr bitmapfile FileName icons iconl png The Speaker class will show the speaker picture on the screen Soutput true class Speaker Core Group The Image object to view the Iconl bitmap resource object Views Image Image preset Bounds lt 0 0 64 64 gt preset Bitmap Sample Iconl1 preset Visible true inherited property Visible true Respond to KeyDown events and toggle the visible state of this group inherited method HandleEvent var Core KeyEvent keyEvent Core KeyEvent aEvent Is this a KeyDown event if keyEvent null amp amp keyEvent Down Visible Visible return this Sign this event as unhandled return null Embedded Wizard Copyright TARA Systems GmbH Page 83 Chora User Manual www embedded wizard de Statements TARA Systems 5 Statements The statements of a Chora program control the flow of program execution The programmer uses the statements to define the logic of a method In Chora as in other programming languages several kinds of statements are available to perform loops to select other statements to be executed etc Here is a brief overview of supported Chora statements
239. s bricks in the Project Composer window Embedded Wizard Copyright TARA Systems GmbH Page 16 Chora User Manual www embedded wizard de Project file EWP TARA Systems The attributes of the styles can be set directly in the Inspector window when the appropriate style brick has been previously selected AquaStyle style 15 P German language 14 P Default language 13 Win32_Index profile 12 sl Brick lt 340 110 480 150 gt Generator true e Generator The code generation attribute determines how this selected member is handled by the Code Generator Ble Description 3 5 Comments Comments may be added to all units profiles macros languages and styles Such comments are preceded by a double slash and extend to the end of the line of code The unit Core contains base classes View Group Root and Timer unit Core attr Directory Mosaic Unlike other programming languages the comments given are not ignored or simply bypassed Instead they are read by the Chora compiler and output in the generation of the ANSI C code From Chora s standpoint comments are fully valid syntactic elements For this reason it is not allowed to write a comment just anywhere in a project file This excerpt from an erroneous project file demonstrates this unit Core attr Directory Mosaic Misplaced comment Embedded Wizard Copyright TARA Systems GmbH Page 17 Chora User Manua
240. sly selected D Thirditem item D Secondltem item 1 MenuCaption const string 24 HelloWorld class Coe Boot 23 gt D Firstltem item bottom Brick lt 170 110 310 150 gt Brick lt 160 10 300 50 gt Description This is an enumeration Description Second item of th Generator falsel e Default 5 Generator The code generation attribute determines how this selected member is handled by the it a Default Stores an optional initialization value for the enumerator item Embedded Wizard expects here an unsigned number e g it Description E Description 4 7 Sets Sets are always introduced using the keyword set followed by the name of the set itself set States item Visible item Selected item Highlighted Here we have defined a new set named States The set consists of 3 elements the so called enumerators with the names Visible Selected and Highlighted A set is a user defined data type This data type can be used to declare variables that will contain any combination of enumerators from the set var Sample States states states Sample States Visible Highlighted The above example demonstrates how a variable with the user defined set data type Sample States is declared After the declaration the variable may contain only elements from this set Other values are not allowed and will be seen as errors by the Chora compiler as for example in this attempt to co
241. ssing it can happen that multiple case statements are executed one after the other until either a break or the end of the switch statement is reached Used reasonably this technique contains potential for some programming tricks On the other hand forgotten or wrongly placed break statements are a common source of logical runtime errors For this reason Chora does not allow break statements and every case default statement is neatly ended automatically In rare cases it is desirable to define multiple different conditions for a single case statement If this condition is fulfilled the switch statement automatically branches off to the corresponding case statement In order to define a case statement with several conditions the constants it contains must be separated by commas when listed behind the case keyword If the expression event Code in the following example gives the value Core KeyCode Ok or Core KeyCode Menu the method OpenMenu is called in both cases Embedded Wizard Copyright TARA Systems GmbH Page 93 Chora User Manual www embedded wizard de Statements TARA Systems var Core KeyEvent event Handle the user input switch event Code case Core KeyCode 0Ok Core KeyCode Menu OpenMenu case Core KeyCode Red Core KeyCode Yellow Core KeyCode Blue Core KeyCode Green OpenDialog Otherwise th vent remains unhandled default return null
242. ssion The result of this expression allows an additional subdivision of observer groups In the following example the slot methods are attached as observers for two different global notifiers The identity of these notifiers is specified by the last operands First register two observers attachobserver updateThis null 1 attachobserver updateThat null 2 Then notify the observers with the ID 2 In response to this the slot method updateThat will receive a signal updateThis will not notifyobservers null 2 The optional id operand can also be used together with an object or a property reference In this case several independent groups of observers may exists all attached to one and the same object or property The determination of the affected group is performed on the basis of the optional id operand Embedded Wizard Copyright TARA Systems GmbH Page 107 Chora User Manual www embedded wizard de Statements TARA Systems attachobserver update controller 1369 If the optional operand is missed the value 0 zero is assumed automatically attachobserver update controller It will work The slot method update will receive a signal notifyobservers controller 0 The concept of observers extends the Chora concept of signals It provides a fundament for the development of applications which use the Controller View model 5 19 detachobserver statement The detachobserver statemen
243. stant Metod ET 144 7 9 Instant propertie TEE 147 7210 INdex ETC TE 156 LAT ASSIQNIMEN OPCLAOM 2icins fees caves shia dcg a diapegehinhcgens aueegeetuneedheaty 158 Pale pareant tie ee 159 AS classer OPeCralO TEE 159 ent MET e Done e EE 159 8 Chora DIED MOCSSSOM ce 2aeds sn ececcet acer dei dec ve ecensanccenetee vectsehe nnne 161 8 1 Macro E EE 161 8 2 Preprocessor CIreGliVGS i iin sdecsiciisceeish ec ede senadeenicdis SEENEN SEENEN ENEE 167 Regel Bee 170 9 Language selection EE 174 10 Usage of Ee nere nnee nenene nnne con soceacaienne st sereeanes 179 11 Garbage collection ssi cccadsendneeass mecsssseeciers ave eccuaeeseteeenscareeeen eens 185 12 eu Tu EE 187 13 E le ul E e 190 Embedded Wizard Copyright TARA Systems GmbH Page 3 Introduction TARA Systems 1 Introduction Chora is a universal object oriented programming language for developing graphical user interfaces GUIs and so called on screen displays OSDs for embedded systems Programmers use Chora to describe the appearance and behavior of the GUI It defines the position size color and font of graphical GUI objects and describes how these objects should communicate with one another and react to user interaction A special Chora compiler then translates the GUI description into the ANSI C language and enables simple integration of the GUI within an embedded system The Chora programming language is not restricted to any specific target platform An GUI created with Chora
244. stems GmbH Page 124 www embedded wizard de Operators TARA Systems rect point point point color color styles styles set set Embedded Wizard Chora User Manual c a b c 118 Rectangle movement The result is the reci operand moved by the offset given in the poini operand The movement will be done in the negative direction CT CT var rect a lt 10 20 30 40 gt var point b lt 5 7 gt var rect c Se a b Ze lt 5 13 25 33 gt Point movement The result is the left point operand moved by the offset given in the right point operand The movement will be done in the negative direction var point a lt 10 20 gt var point b lt 5 7 gt var point c c a b c lt 5 13 gt Color subtraction with saturation The subtraction will be done separately for each color component In the case the subtraction results in a value lt 0 the value will be adjusted automatically to 0 saturation var color a 10CO50FF var color b 225F2200 var color c c a b c 00612EFF Difference between two styles sets The result is a new styles set which contains the style names enclosed only in the left operand var styles a Aqua Win95 var styles b Win95 var styles c c a b c Aqua Difference between two sets The result is a new set which contains the enumerators enclosed only in the left operand var Unit Align
245. such as string color rect etc gt please refer to the chapter titled Instant data types chapter 6 1 gt Acomprehensive set of operators that can be used to evaluate expressions from simple arithmetic logical operators etc to complex instant methods instant constructors object cast etc gt please refer to the chapter titled Operators chapter 7 gt User defined enumeration and set data types gt please refer to the chapters titled Enumerations chapter 4 6 Sets chapter 4 7 and User defined data types chapter 6 2 gt Instructions to control the program flow for and while loops local variables etc gt see Statements chapter 5 gt Signals and slots for simple communication between objects An object may send signals to slots of other objects without necessarily knowing the identity of the recipient object gt see signal statement chapter 5 11 and slot methods chapter 4 1 5 4 Embedded Wizard Copyright TARA Systems GmbH Page 5 Chora User Manual www embedded wizard de Introduction TARA Systems gt Pending signals for deferred code execution The signals are delivered before or after the screen update is performed depending on the used statement gt see postsignal statement chapter 5 12 and idlesignal statement chapter 5 13 gt Reference data types are also useful for communication between objects With the aid of a reference it is possible to acc
246. t chapter 5 12 and idlesignal statement chapter 5 13 Within the Embedded Wizard IDE the slot methods appear as bricks in the Class Composer window The attributes of the slot method can be set directly in the Inspector window when the appropriate method s brick has been previously selected IsActivated var bool 122 wi ColorEffect object Effects ColorEff 121 Sheep object Sheep Sheep 120 Action slot 119 a Brick lt 340 130 480 170 gt Description The responder for all Menu It Generator false Native false 7 Native The native attribute determines whether this method contains a pure Choral code or the target dependent native code e g e Description bai The logic of the method can be implemented in the Editor window after the method brick has been double clicked Embedded Wizard Copyright TARA Systems GmbH Page 49 Chora User Manual www embedded wizard de Unit file EWU TARA Systems slot DemoMenu MainMenu Action var Menu Menu menu null IG f f Which menu item has fired the signal i Itemi menu Item2 menu Item3 menu Item menu Item5 menu if sender d sender sender sender sender new DemoMenu LanguageMenu new DemoMenu VideoMenu new DemoMenu AudioMenu new DemoMenu RatingMenu new DemoMenu HelpMenu ff Make the submenu wisible var Core Root r GetRoot r Add menu 3 r Focus menu 4 1 5 5 Init constructors The
247. t be converted to int32 The result is different in each case 5 1369 and 5 Not every type conversion is allowed Many of the data types integrated into Chora language are so different that a type conversion applied between the data types would not make much sense Thus for example it is possible to transform an int32 number into a string whereas a conversion from color into string is not allowed var string text var int32 volume var color bgColor text Volume level text The color is tring volume Ok tring bgColor Error n n The following illustration shows the type conversions that are possible among the data types No other Chora instant data types can be converted Figure 7 1 Aside from explicit type conversion it is possible to subject the operands in an expression to an automatic implicit type conversion without having to use the instant cast operator For example the Chora compiler knows that when a value is assigned to a variable the data type of the assigned value and the data type of the variable in which the value is to be stored must match If this is not the case Chora will attempt to perform an appropriate implicit type conversion in order to match the assigned value to the variable s data type This process is analogous to use of the instant cast operator Embedded Wizard Copyright TARA Systems GmbH Page 134 Chora User Manual www embedded w
248. t de registers a slot method from the given property or object The syntax for the detachobserver statement has three forms Form 1 detachobserver slot method object id Form 2 detachobserver slot method property reference id Form 3 detachobserver slot method null id These three forms differ in the type of the affected source In the first case the slot method is detached from the object object In the second case the observer will be detached from the property specified in the expression property reference The third form allows the de registration of a global object and property independent observer detachobserver update controller VolumeLevel The example above demonstrate the usage of the statement to de register the slot method update from the property VolumeLevel of the object controller As soon as the observer has been detached it is not able to receive any notifications anymore If the detached observer has been notified shortly before the pending signal will always be delivered even the observer has been detached in the meantime Notify all affected observers after this signals are waiting for the delivery notifyobservers controller VolumeLevel detachobserver update controller VolumeLevel Embedded Wizard Copyright TARA Systems GmbH Page 108 Chora User Manual www embedded wizard de Statements TARA Systems Although the observer has been detache
249. t is executed zero or more times until a condition becomes false You can use additional expressions within the for iteration statement to initialize and change values during the for iteration statement s execution gt while iteration statement gt The while iteration statement lets you repeat an other statement a specified number of times The body of a while iteration statement is executed zero or more times until a condition becomes false gt return statement gt The return statement terminates the execution of a method and returns control to the calling method Execution resumes in the calling method at the point immediately following the call A return statement can also return a value to the calling method gt signal statement gt The signal statement is for sending signals to a selected slot of an object Together with the slot method this command forms a simple method for communicating between objects Embedded Wizard Copyright TARA Systems GmbH Page 84 Chora User Manual www embedded wizard de Statements TARA Systems gt postsignal statement gt The postsignal statement records a pending signal to a selected slot of an object The signal is delivered always immediately before the screen update is performed Unlike the ordinary signal statement postsignal is suited for deferred code execution for example to finalize some initialization steps gt idlesignal statement gt The idlesignal statement records a pend
250. t is defined Thus in the example only the Caption variable has been given an initial value of Video Settings lf an object of the Item class is created at runtime the object s Caption variable is automatically given the value of the character string Video Settings at the time of creation Variables that are not explicitly given an initial value are assigned a default value of 0 zero A non explicitly initialized string variable if there is no initialization of Caption would thus contain an empty string Chora defines a set of data types Any of these data types may be used to define a variable A detailed description of these data types can be found in Data types chapter 6 Access to a variable always occurs within the context of the object to which the variable belongs var Sample Item theObject new Sample Item theObject Caption Sound Settings Because each object stores its own copy of its variables Chora does not allow the definition of global variables Changing an object s variables has no effect on the variables of other objects var Sample Item objectl new Sample Item var Sample Item object2 new Sample Item theObject1 Caption Sound Settings If therefore as the above example demonstrates the Caption variable of object1 is changed this has no effect on the contents of the second object object2 Its Caption variable still contains the original initializat
251. ta to an ANSI C code In case of a PNG file or GIF the resource converter also evaluates the transparency information stored in the file s alpha channel If no alpha information is available in the bitmap file you can provide it in a separate bitmap file specified in the following AlphaName attribute If FileName attribute was ommited and an AlphaName attribute specified the resulting bitmap resource is considered as alpha bitmap only gt the bitmap will contain transparance information only Please note this feature is supported together with the new Graphics Engine 2 0 only If the file name contains a relative path the bitmap file will be looked for relative to the directory of the unit file where the bitmap resource is defined This optional attribute contains the name of an additional BMP PNG GIF or JPG file that is interpreted as the transparence mask alpha channel for the origin bitmap specified in the attribute FileName If FileName attribute was ommited the resulting bitmap resource is considered as alpha bitmap only gt the bitmap will contain transparance information only If this optional bitmap is specified the resource converter evaluates the gray values of its pixel as transparence information for the corresponding pixel of the origin bitmap In this case the black color stands for a full transparent pixel and the white color corresponds to a pixel with a full opacity Please note this featu
252. tement results in the value nu11 then no pending signal is recorded and program execution continues without resulting in any runtime errors var slot theSlot null The variable theSlot can still keep null sometimes if visible theSlot theObject OnAction Try to record the signal idlesignal theSlot The pending signals are delivered strictly in the order in which the corresponding idlesignal statements are executed Multiple signals to the same slot will be always merged together and delivered as a single signal lf a signal is already pending for the delivery the idlesignal statement does not record it twice it moves the recorded signal to the end of the list of pending signals only The example below demonstrates these aspects Record signals to the slots OnActionl OnAction2 and OnAction3 idlesignal theObject OnActionl idlesignal theObject OnAction2 idlesignal theObject OnAction3 Since OnActionl already waits for the delivery the following statement does not record the signal twice It only changes the order of the signal delivery idlesignal theObject OnActionl Due to the last idlesignal statement OnActionl1 is moved to the end of the list of pending signals When executed the signals are delivered in the following order OnAction2 OnAction3 OnActionl Unlike the ordinary signal statement idlesignal does not pass the sender of the signal to the affected slot
253. the method returns true Toggle the Aqua style in the global styles variable if styles contains Aqua styles styles Aqua else styles styles Aqua In the above example the operators and have been used to build a union or a difference of two styles sets A more simple way to toggle a style can be implemented by using the exclusive OR operator styles Aqua styles The supported operators are described more detailed in Binary instant operators chapter 7 2 During the development the styles can be activated and deactivated in a convenient way directly in the Styles combo box of the Embedded Wizard IDE IE 2 Che RGBA v AquaStyle GE Me qua tyle Laf on i lb Aside from the global variable styles there is also an instant data type of the same Ok name styles This data type is used whenever variables properties or arrays must be defined in order to store there the names of active styles Ko class DemoMenu Mainde Store the currently active styles in the temporary variable var styles tmp styles switch the styles styles WideScreen Ne Do something here Restore the previously active styles styles tmp The handling of multivariant classes and resources is performed in the same way as this was demonstrated in the examples above Assumed the class Menu MenulItem is multivariant
254. the data types is of great importance when defining constants variables or properties Each definition requires explicit information regarding the desired data type With this information the Chora compiler is able to recognize what content a variable will have in the target system and can recognize when operations are performed on a variable that are invalid for its data type The choice of supported data types fits the requirements for development of GUls For this reason the language supports three different kinds of data types gt Instant data types gt The instant data types are an integral part of the Chora programming language and can be used in any program without additional definitions They can t however be changed gt User defined data types gt The user defined data types include classes enumerations and sets The programmer may define an arbitrary number of data types to use in a Chora program gt Reference data types gt Allow the building of links to object s properties in order to access these properties In this way it is possible for one object to use a reference to read or write the property of another object without needing to know anything about the existence of that object 6 1 Instant data types The instant data types are an integral part of the Chora programming language The choice of instant data types is attributable to the application field development of 2 dimensional graphical user interfaces
255. the extent union union extent Continue with the next view tmp tmp next Note that the content of a variable is lost when the block is left As a result it is not possible to define global or static variables All variables are automatically defined when the block is entered and removed when the block is left 5 2 array declaration statement An array statement is for declaring a local array The array can then be used in the method s logic to store intermediate results for example The array statement uses the following syntax array type expression name array size The array s data type is given explicitly with type expression Chora defines a set of data types All of these data types may be used when defining a local array A detailed description of the data types is found in Data types chapter 6 Unlike a variable an array can store more than one value To do this the maximum size of an array must be given explicitly in its definition The following example demonstrates the definition of an array with the name points The array consists of a total of 16 elements each of which stores a floating point value array float points 16 The elements of an array must always be initialized before use in an expression The Chora compiler will report an error if a non initialized array item is used in an expression The following example demonstrates the initialization of a local array with the 0 0 value
256. tic elements They are used as the inline documentation for languages units profiles constants resources classes methods properties etc This documentation is displayed in Embedded Wizard application in the Short Info area of the Inspector window Each time a member is selected in the Composer window the associated documentation will appear in the Short Info area immediately The more important use case for the comments is the automatic generation of the documentation file Embedded Wizard evaluates the content of your project the dependencies between the classes constants resources etc and stores it together with the associated inline documentation within a set of HTML files In the second step a single MS Windows help file is created This help file contains detailed documentation of your project and it can be used or distributed as the Software reference manual For more details how to generate the documentation file see the Embedded Wizard User Manual During the generation of the documentation file the content of all affected comments is preprocessed by the Embedded Wizard In this manner cross references are added and additional formatting of the text of the inline documentation occurs For this preprocessing following rules are used 1 While formatting all text lines of the inline documentation are converted in HTML paragraphs Within the comment a single text line is always terminated by the carriage return
257. tion operator a reference is dereferenced whereby the contents of a property may be read or written Because every access to a property necessarily invokes a relevant onget or onset method dereferencing of references automatically invokes the relevant method Please note that dereferencing a null reference will cause a runtime error i e panic At runtime you can test whether a reference has been correctly initialized and is not preset to nu11 if RefToString null RefToString Hello world Embedded Wizard Copyright TARA Systems GmbH Page 118 Chora User Manual www embedded wizard de Data types TARA Systems The Chora programming language allows only simple references meaning the references may not be nested Creating a reference to another reference is therefore illegal var color RefToRefToColor Menu BackgroundColor In such a case the Chora compiler will report an error message For additional details see Properties chapter 4 1 3 Embedded Wizard Copyright TARA Systems GmbH Page 119 Chora User Manual www embedded wizard de Operators TARA Systems 7 Operators Handling of the instant and user defined data types is noticeably simplified by the operators integrated within Chora language The programmer uses the operators to construct complex expressions consisting of different operands Thus the programmer can for example define complicated arithmetic operation Just as easily he can combine
258. tive void Done Sif Splatform Tara Win32 release the timer KillTimer Sendif Destructors are invoked automatically by the Chora Runtime Environment shortly before an object is destroyed in order to give the object the chance to release resources it is using It is unnecessary and even undesirable to call destructors directly from within the Chora code This can lead to inexplicable runtime errors var Core Timer timer new Core Timer DON T call destructors directly timer Done It must be noted that the Chora Runtime Environment contains a Garbage Collector that is responsible for disposing of all objects that are no longer in use This Garbage Collector analyses the dependencies between all objects and recognizes which of these objects are no longer needed in order to subsequently destroy them Garbage collection is automatically activated by the Chora Runtime Environment when needed It is thus not possible to predict the exact point in time when unused objects will be destroyed Depending on the target system and the implementation of the Garbage Collector unused objects may remain in memory for some time until the Garbage Collector identifies and destroys them As a result possible calls to the destructor may be delayed accordingly The point in time when the destructor is called can thus not be predicted Since destructors are optional the absence of destructors does not lead to an e
259. tmap is signed as not animated Table 4 1 Within the Embedded Wizard IDE the bitmap resources appear as bricks in the Unit Composer window resource Resources Bitmap J Thelcon The attributes of the resource can be set directly in the Inspector window when the appropriate resource s brick has been previously selected Embedded Wizard Chora User Manual Copyright TARA Systems GmbH Page 60 www embedded wizard de Unit file EWU TARA Systems VideoMenu class Menu Menu 2 zz LanguageMenu class Menu Menu 1 MainMenu class Menu Menu bott Thelcon resource Resources B 24 e Brick lt 40 90 180 130 gt Description This is a bitmap resource Generator false ResourceClass Resources Bitmap AlphaName FileName ImageFile pngl DI FrameDelay FrameSize FileName The path to a BMP PNG or JPG file The resource converter will read this file and convert the pixel data to an ANSI C code In v Description bai 4 3 2 Attributes of a font resource A resource of the class Resources Font supports the following attributes Attribute name FontName Quality Height Bold Italic Embedded Wizard Chora User Manual Description This attribute contains the name of a Microsoft Windows font The desired font must exist and already be installed under Windows Only TrueType fonts are allowed Any attempt to convert a bitmap font results in an error The Quality attribute
260. to a property always occurs in the context of the object to which the property belongs var Sample Item theObject new Sample Item theObject Caption Sound Settings From the programmer s perspective a property can be compared with a variable gt properties are handled the same as simple variables The difference between variables and properties lies in the strict use of the onget and onset methods Each property must define one onget and one onset method The logic of these methods is automatically executed when the property s value is read or when a new value is assigned to the property The programmer uses the onget and onset methods to handle access to the property in a particular way For example he can react to changes to the Caption property by having the screen refreshed Embedded Wizard Copyright TARA Systems GmbH Page 30 Chora User Manual www embedded wizard de Unit file EWU TARA Systems class Item property string Caption Video Settings onget Caption return pure Caption onset Caption pure Caption value And now redraw the screen to display new Caption UpdateScreen In spite of the fact that any access to the property occurs by means of the onget or onset method each property just as with a variable has its own area in memory in which the property s value can be kept In order to access this area of memory the keyword pure must be used With this keyword th
261. tores the content of the macro Embedded Wizard will replace all occurrences of this macro with this content automatically Description a 3 3 Languages A language is always introduced by the keyword language followed by the name of the language itself language English This defines a language named English The name of the language can now be used in the definition of constants and resources in order to label the language dependency Please note that each project must define at least one language that has the name Default in which Default fulfills a special purpose The default language will be used for all non language dependent GUIs More details can be found in Language selection chapter 9 Optionally the language definition may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled Soutput true language English For more details about the output directive see Control directives chapter 8 3 Within the Embedded Wizard IDE languages appear as bricks in the Project Composer window Embedded Wizard Copyright TARA Systems GmbH Page 15 Chora User Manual www embedded wizard de Project file EWP TARA Systems The attributes of the language can be set directly in the Inspector window when the appropriate language brick has been previously selected AquaStyle style 15 German
262. translate it to ANSI C A project file must always begin with a version directive This directive informs the Chora compiler of the syntax used in the project file and is intended for the future file extensions The directive is followed by the version number For example Sversion 5 0 If the Chora compiler does not recognize the version number given the translation is aborted with an error message After the version directive follows the actual listing of the project s components These include gt Units gt Each unit file used in the Chora program must be defined explicitly in the project file Only in this way can the Chora compiler access all relevant units The definition of a unit comprises the indication of where within the file system the EWU unit file may be found gt Profiles gt A profile describes the settings of the desired target platform The target platform is determined from the name of the so called Platform Packages A Platform Package is an Embedded Wizard extension that must be supplied by TARA Systems GmbH for each target platform Besides the name of the Platform Package used a profile may contain a set of settings and macro definitions gt Macros gt A macro stores any character string under a unique reference name By using this reference name the contents of the macro the character string stored there can be used in definitions of classes methods and so on A macro is always defined within a pr
263. ttribute the Code Generator may perform different code simplification and elimination steps Following optimization levels are available None Optimization is disabled Low Simple optimization Medium Medium level of optimization High High level of optimization The Sobfuscation macro is replaced by either the value true or the value false depending on the Obfuscation attribute of the currently selected profile Copyright TARA Systems GmbH Page 165 www embedded wizard de Chora preprocessor TARA Systems SApplicationClass SApplicationTitle SApplicationName SScreenSize SClut The obfuscation attribute controls the format of the generated code If this attribute is true the Code Generator will try to compress and obfuscate the generated code If this attribute is set false the code is not modified The effect of this attribute depends on the used Code Generator If the generator doesn t support the code obfuscation then the attribute has no effect on the generated code true obfuscation mode is on false obfuscation mode is off The SApplicationClass macro is replaced by the value of the ApplicationClass attribute of the currently selected profile This attribute defines the root class of the entire GUI application The SApplicationTitle macro is replaced by the value of the ApplicationTitle attribute of the currently selected profile This attribute defines the optional
264. u Item sign object Menu Menultem 118 object Menu Menultem 117 sl lt 340 130 480 170 gt false false Copyright TARA Systems GmbH Page 189 www embedded wizard de Optimization TARA Systems 13 Optimization In order to generate compact and fast code for the target system an optional optimization is available and can be explicitly enabled The optimization level is controlled by the profile s attribute Optimization Each profile within the project may define a different optimization strategy depending on its Optimization attribute The Optimization attribute may take one of the following values also called optimization levels Optimization level Description None No optimization is performed This is the default optimization level which ensures the best possible compatibility to older versions of Embedded Wizard Low Performs simple optimization steps gt All invocations of non overridden methods are performed directly without the VMT virtual method table indirection gt The read write access to properties is performed directly without the invocation of the onget or onset methods if these methods contain only a single pure expression to access the property s value and these methods are not overridden in derived classes Medium This optimization level forces the reorganization of the layout of Chora objects in order to reduce their size and the RAM usage The exact behavior of this opt
265. ul if deferred code execution is necessary For example during the initialization of the GUI application some initialization steps may be finalized later still before the screen update is performed To force code execution after the screen update is done the statement idlesignal should be used For more details regarding the slot methods see slot methods chapter 4 1 5 4 5 13 idlesignal statement An idlesignal statement records a pending signal to an object for a deferred delivery The signal is delivered as soon as possible after the screen update is performed and no user inputs are waiting for the execution When the signal is delivered it is sent to a slot of an object using the corresponding slot method The idlesignal statement has the following syntax idlesignal expression The expression in the idlesignal statement must result in data type slot otherwise the Chora compiler will indicate an error The following example demonstrates the use of the idlesignal statement to record a pending signal to the OnAction slot of the object theObject Embedded Wizard Copyright TARA Systems GmbH Page 99 Chora User Manual www embedded wizard de Statements TARA Systems var slot theSlot theObject OnAction Record a signal to the OnAction slot of the theObject object idlesignal theSlot Note that in Chora it is not absolutely necessary to react to a signal that is sent If the expression in the idlesignal sta
266. umeration it is necessary to assign a designated numeric value to the appropriate item In such case the Code Generator takes over the given number and uses it for the enumeration of all following items set States tem Visible item Selected 0x100 tem Highlighted H H The above example demonstrates the explicitly designation of a numeric value to an item within an set definition In this case the second item Selected has become a value 0x100 256 This will force the Code Generator to use the specified value for all occurrences of the item within the generated code As mentioned above the Code Generator also uses the specified value for the enumeration of all following items Therefore the third item Highlighted will receive the value 0x200 512 Optionally the set definition may be prefixed with the output directive This directive controls the code generation for the affected definition it is generated if the condition of the directive is fulfilled output true set States For more details about the output directive see Control directives chapter 8 3 Within the Embedded Wizard IDE the set definitions and their item enumerator members appear as bricks in the Composer window set ies Set g Firstitem The attributes of these definitions can be set directly in the Inspector window when the appropriate brick has been previously selected Embedded Wizard Copyright TARA Systems GmbH Pa
267. und in Unit file EWU chapter 4 Tabelle 8 3 Copyright TARA Systems GmbH Page 173 www embedded wizard de Language selection TARA Systems 9 Language selection The Chora programming language supports the development of multilingual GUI applications A multilingual GUI application contains GUI definitions with texts images etc for various languages At the application s runtime it is then possible to switch between the different languages A German user for example will select the German language while a French user will prefer French The development of a multilingual GUI application requires that all desired languages are listed explicitly in the project file This is done using the keyword language language German language French language Greek language Default Note that the language Default has a special importance and must always be defined This Default language stands for all parts of the GUI application that are not language dependent A precise description of how languages are defined can be found in the chapter Languages chapter 3 3 Chora s multilingual function is limited to the definition of constants and resources This means that only constants and resources may have multiple language dependent contents For example a constant string with text in German and English const string Caption German Hallo Welt Default Hello World 1 Multilingual resources are defined
268. variant directive allows the implementation of multivariant classes A single class can be overridden by multiple variants Which variant is finally used is determined during the code generation and at the runtime In this case we distinguish between static and dynamic variants Static variants depend on profiles and dynamic variants on styles For more details about the variant directive see Control directives chapter 8 3 In Chora it is also possible to derive a class variant from another class variant This results in very powerful instrument for the development of multivariant GUI applications Embedded Wizard Copyright TARA Systems GmbH Page 73 Chora User Manual www embedded wizard de Unit file EWU TARA Systems Within the Embedded Wizard IDE class variants appear as class bricks extended by a small icon in the Unit Composer window A double click on the class variant brick will show its class members and if the class contains graphical objects these objects are also drawn on the screen The attributes of the class variant can be set directly in the Inspector window when the appropriate variant brick has been previously selected MenuVariant vclass DemoMenu Menu Menu class Menu Menu ER Thelcon resource Resources Bitm 31 sl Brick lt 560 340 710 380 gt Description MultiLingual false VYariantCond true VariantOF DemoMenu Menu v YariantOf The name of the ancestor of this variant This
269. y commas Field 0 2 1369 If possible omit the usage of multi dimensional arrays because of possible changes in the future implementation of Chora The current implementation of arrays will be then replaced in order to support dynamic and open arrays 5 3 Expression statement Expression statements cause expressions to be evaluated No transfer of control or iteration takes place as a result of an expression statement Embedded Wizard Copyright TARA Systems GmbH Page 88 Chora User Manual www embedded wizard de Statements TARA Systems All expressions in an expression statement are evaluated and all side effects are completed before the next statement is executed The most common expression statements are assignments and method calls Bounds lt 0 0 200 100 gt Clipping lt 10 10 20 20 gt var reci var reci UpdateArea Bounds lt 5 2 gt amp Clipping This example demonstrates how the rectangle stored in the variable Bounds is moved a distance of lt 5 2 gt pixels and then forms an intersection with a second rectangle Clipping The result of this expression is passed to the method UpdateArea 5 4 Empty statement An empty statement is a statement containing only a semicolon it can appear wherever a statement is expected Nothing happens when an empty statement is executed The correct way to code an empty statement is D r Statements such as while for if require that an executable statement a
270. ypes of both operands must match so that the comparison can be done var string a Hello var string b World var bool c c a bi c false Opl Ir Op2 Not equal to The result of Op1 Op2 is true if any datype both operands are different This operator can be used for all data types The data types of both operands must match so that the comparison can be done var string a Hello var string b World var bool c c a b c true Ges rect point g point in rectangle test The result of this point i rect expression is true if the given point does not lie within the area of the rect operand var rect a lt 0 0 100 200 gt var point b lt 10 20 gt var point c lt 200 300 gt var bool d d a b d false d a c d true lt int lt int Less than The result is true if the left operand is float lt float e we less than the value of the right operand Both operands must be arithmetic Embedded Wizard Copyright TARA Systems GmbH Page 130 Chora User Manual www embedded wizard de Operators TARA Systems lt string lt string gt Pint gt Pint float gt float char gt char gt string gt string E Pint lt int float lt float char lt char lt string lt string Embedded Wizard Chora User Manual var int32 a 1369 var int32 b 1251 var bool c c a lt b c false Less th

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