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smalltalk-80 system

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1. 20 Communicating with the 4404 File System 2 21 Listing Files an l l 21 Writing Files Out to the 4404 Operating System 22 Manipulating Windows Themselves 22 23 Saving Your Work and Quitimg 22 24 PROGRAMMING IN THE SMALLTALK 80 SYSTEM 25 Getting into the Smalltalk 80 System on the 4404 25 Invoking the Smalltalk 80 system for the First Time 26 Installing Your Own Image 27 Hints Helps and Tips for Smalltalk Programmers 28 Managing Your Image and Changes Files 28 Modifying your Changes File 2222 28 If You Cannot Bring Up Your Image 5222 29 Enhancements to the System Workspace 29 4404 Smalltalk 80 System User s ii Miscellaneous Programming Tips 30 Debugging Smalltalk Code eu AR ss 30 Redefining a a O aa oan 31 Uploading Files to Another Computer System 31 Errors in the Addison Wesley Books 31 Multiple Inheritance of Classes ua aa
2. 5 Special Purpose A EA 5 Kop U Menus 6 The Smalltalk 50 Language ic AYA R A k 6 Obyets and Classes az l 6 Methods and Messages 7 The Syntax of the Smalltalk 80 Language 2222 7 An Example of Smalltalk Code 00 0 eeeeeseeeeeeeeeeesnsscsecseeesessnereeeeees 7 THE 4404 SMALLTALK 80 SYSTEM A TUTORIAL 5 11 How to Get the Most Out of This Tutorial 2 11 Tutorial on the 4044 Smalltalk 80 System 22 11 Getting Into the Smalltalk 80 System 2222 12 Learning Mouse Mechanics 12 What the Mouse DuttonsDou 14 How to Select Smalltalk Objects UUU A S A Dax l 14 How to Scroll Text in a VVindev Ras 15 How to Find Out About Classes and Messages 15 Running Some Code Already in the System 17 Clearing the Display R A m 19 Altering and Running Some Smalltalk Code 2 19 PARC a Short Break R y AR dasmaq 19 Opening a Workspace Window 20 Evaluating Smalltalk Expressions in a Workspace 20 Manipulating Code or Text in a Workspace
3. Browser organization category className meta protocol selector TextMode Debugger context receiverlnspector contextInspector shortStack sourceMap sourceCode processHandle MethodListBrowser methodList methodName Change position ClassRelatedChange className ClassChange ClassDefinitionChange superclassNam e classType otherParameters ClassOtherChange type ClassCommentChange MethodChange selector category MethodDefinitionChange MethodOtherChange type OtherChange text ChangeSet classChanges methodChanges classRemoves reorganizeSyster specialDolts Checker 0 ClassCategoryReader class category ClassOrganizer globalComment categoryArray categoryStops elementArray SystemOrganizer Collection Bag contenis 54 4404 Smalltalk 80 System User s Smalitalk Classes List MappedCollection domain map SequenceableCollection ArrayedCollection Array ByteArray CompiledMethod RunArray runs values String Symbol 0 Text string runs WordArray DisplayBitmap Interval start stop step TextLinelnterval internalSpaces paddingWidth LinkedList firsiLink TastLink Semaphore excessSignals OrderedCollection firstindex Tastlndex SortedCo
4. The joydisk in the upper lefthand corner of the keyboard is another way to move the whole display at once What you are observing is a 640 by 480 sized pixel window into the Smalltalk 80 system s 1024 by 1024 bitmap display This hardware panning is completely independent of the Smalltalk 80 system and may be done at any time 4404 Smalltalk 80 System User s 13 The 4404 Smalltalk 80 System A Tutorial VV hat the Mouse Buttons Do 12 The three buttons on the mouse give you access to many of the Smalltalk 80 system s functions The left button is used mainly to select something some text some code a window etc The middle button is used mainly to pop up a menu dealing with what you can do to the contents of windows And the right button is used mainly to pop up a menu dealing with what you can do to a window itself A good vvay to manipulate the mouse is to grasp it betvveen your thumb and middle finger and then to press the buttons with your index finger After you work with the mouse for a while you may find that another way works better for you The point of the mouse is to facilitate quick interaction vvith the Smalltalk 80 system use the mouse the way it works best for you Each button has two states pressed and released When you work with the mouse be ready to press and hold a button down You release the button after you have decided with the middle and right buttons what command you want to do The general
5. bic Pen new bic mask Form gray bic defaultNib 4 bic combinationRule Form under 1 to 50 do i i bic go i 4 bic turn 891 Pen example 5606 3 Figure 3 System Browser Window clicking on ged or cm At this point if you like you can go back to the message category pane click vvith the left button on a different message category and then click on any new message selector you see in the message selector pane You use this feature of the System Browser constantly as you learn about the code in the system Running Some Code Already in the System 21 22 If you have read through Section 2 you will remember that a method whose message selector is example was examined Now use the System Browser to find and run that piece of code Go to the class category pane the leftmost one and click with the left button on the category Graphics Primitives You may have to use the scroll bar to find the category in the list Next click on the class Pen Be sure to also click on the class box in the class names pane Then click on examples in the message categories pane and example in the message selectors pane In the bottom pane you should now be looking at the example method for the class Pen See Figure 3 To run this example of Smalltalk code look to the end of the code and find the text Pen example Highlight just the Smalltalk expression Pen example not example that is do not include the double q
6. Refer to the Goldberg and Robson book for more information about this The effect of this line of code is that the Pen object bic draws on the surface of the display and is not hidden or obscured by images that are there already that is it is ORed with the existing image 1 to 50 do f l bic go 1 4 bic tum 891 This line of code should look reasonably suggestive to you if you know languages like C and Pascal You should recognize it as an iteration loop It says to evaluate the expression within the square brackets fifty times The part of the line enclosed in and including the square brackets is a block and it represents a deferred sequence of operations The block has one argument specified by i and separated from the expressions in the block by a vertical bar There are two expression within this block bic go i 4 and bic turn 89 bic go i 4 means that the Pen object bic should draw in its current direction i 4 pixels bic turn 89 means to alter the current direction by 89 degrees Pen example This is another comment because it is enclosed in double quotation marks but look more closely at it It actually forms a valid expression in Smalltalk code The message selector example is the name of this particular method Thus the code within the quotes says to send the example message to the class Pen Pen looks for a message selector named example finds it and executes the code you have just examined A commente
7. rightIndent tabsArray marginTabsArray outputMedium UndefinedObiect View mode controller superView subViews transformation viewport window displayTransformation insetDisplayBox borderWidth borderColor insideColor _ boundingBox selectionSelected 58 4404 Smalltalk 80 System User s Smalltalk Classes List BinaryChoiceView DisplayTextView rule mask editParagraph FormMenuView FormView rule mask FormHolderView displayedForm ListView list selection topDelimiter bottomDelimiter TineSpacing isEmpty ChangeListView SelectioninListVievv itemLis printitems oneltem partMsq nitialSelectionMsg changeMsg istMsg menuMsg StandardSystemView labelFrame TabelText isLabelComplemented savedSubViews minimumSize maximumSize WindowForm windowFormFiag BrowserView InspectorView NotifierView contenis StringHolderView CdisplayContenits FillinTheBlankVievv ProjectView TextCollectorView WorkspaceView SwitchView complemented label selector keyCharacter TighlighiForm argumente BooleanView TextView partMsg acceptMsg menuMsg CodeView initialSelection OniyVVhenSelectedCodeVlevv selectionMsg WindowingTransformation scale translation 4404 Smalltalk 80
8. TekSystemCall class and system dependent operations Thus these are all methods that are understood by the class TekSystemCall Note that nearly all the method names are taken from the names of system calls as they are documented in the 4404 AIS Reference Manual chacc fileName mode permissions Checks the accessibility of a file with respect to specified permissions chdir directoryName Changes directory to a new directory name chown fileName to ownerlD 42 4404 Smalltalk 80 System User s 4404 Smailtalk Reference Changes the owner of a fileName to ownerID chprm fileName to permissions Changes the permissions for a file close fileDescriptor Closes a file create fileName mode modeBits Creates a new file crPipe fileDescriptor Creates a pipe crtsd newName mode mode addr addr Creates a directory or special file defacc permissions Sets the default permissions as specified by the operating system command perm dup fileDescriptor Duplicates the file descriptor opens the file again dups fileDescriptor with specifiedDescriptor Duplicates the file descriptor specifying the file descriptor of the duplicated open file filfime fileName to time Sets the last modified time of a file fork Creates a new task getild Gets the running task s ID getuld Gets the actual user ID and the effective user ID link fileName to linkName Create a link to a file rec fileDescripto
9. pane and select by clicking on the line with the left mouse button the class category 4404 Smalltalk 80 System User s 15 The 4404 Smalltalk 80 System A Tutorial 19 20 16 Snapshot at 19 November 1984 1 38 09 pm System Workspace FileStream oldFileNamed fileName st edit Changes Modify the internal record of changes Smalltalk noChanges Smalltalk forgetDolts FileStream newFileNamed fileName st fileOutChangesFor Stream Stream removeFromChanges Examine the record of changes Smalitalk browseChangedMessages Smalitalk changes asSortedCollection Collactions Abstract Collections Unordered Collections Sequencea Collections Text Collections Arrayed Collections Stroams Collections Support instance NameOfSuperciass subclass NameofClass instanceVariableNames instVarName1 instVarName2 classVariableNames ClassVarName1 Class arName2 poolDictionaries category Numeric Magnitudes 5606 2 Figure 2 System Workspace Window Numeric Numbers You should see Numeric Numbers highlight if you have successfully selected it Note that the next small pane over now has a list of Smalltalk class names in it In contrast to the class categories the class names are actual Smalltalk 80 language expressions And note also that the bottom pane has what is called Smalltalk template code This is code that you edit and then execute Move the arrow cursor to the
10. 1 of this manual for a comprehensive tutorial introduction and reference to the Smalltalk 80 system What is The Smalltalk 80 System The Smalltalk 80 system is an interactive programming environment It is interactive because it features fast response to the usual tasks of program development creating compiling debugging and running code The system is designed so that usually the only use of the keyboard is to type actual text Other actions are accomplished by operating the mouse buttons to make selections from menus The system is also visually oriented and advantageous feature which allows you to work unhampered by the necessity to remember commands The system is a well designed environment because you interact with the system through a uniform interface to many different functions It is a programming environment because the system is dedicated to creating compiling debugging and running Smalltalk code This makes the Smalltalk 80 system similar to some LISP systems and to the FORTH programming system among others The User Interface Mouse Windows and Menus One of the most striking and distinctive features of the Smalltalk 80 system is the user interface It is visually oriented If you move the mouse around on the mouse pad an arrowhead cursor moves around the screen in concert with the mouse movements You can point at something select it by pressing a mouse button and then do something with the selected object
11. Mode Unshifted Shifted 168 Ctrl Ctrl Shifted 25 F 255 Ctri Shifted 5 Function Key Name F9 10 Mee Unshifted 160 Shifted 172 Ctrl Ctrl Shifted 62 4404 Smalltalk 80 System User s Smalltalk Internal Character Codes B 4 Special Function Keys There are only two special function keys on the Pegasus keyboard One is the up arrow left arrow key in the upper left corner of the main key area while the other is the BREAK key in the lower right corner of the main key area Table B 5 Default ANSI Meanings of Special Function Keys Standard North American Keyboard Function Key Name BREAK Mode Unshifted Shifted Ctrl Ctrl Shifted 4404 Smalltalk 80 System User s 63 INDEX 4404 AIS User s Manual 4404 Documentation 4404 hardware 4404 operating system 4404 Reference Manual Accept command Addison Wesley books Altering text in a workspace ANSI Standard Assignment arrow key Bit mapped display Bitmap Blue book Break points Caps Lock key Centering cursor Centering the cursor Changes file Changing code Classes Classes Categories Classes Definition of Classes Hierarchy of Classes Hierarchy of See also Classes Inheritance of Classes Inheritance of Classes Names Classes Predefined Clicking Definition of Cloned image Commands See Menu commands Commands See Operating system commands Compiling Smalltalk code Contents of manual Controller manager Controller
12. PositionableSiream collection position readLimit ReadStream VVriteStream writeLimit ReadWriteStream ExtemalStream FileStream nam directory mode TileDescriptor TilePosition TileMode FileDirectory Random seed StrikeFont xTabl glyphs nam stopConditions type minAscii maxAscii maxWidth strikeLength descent xOffset raster subscript superscript emphasis SiringHold r contents isLocked ChangeList listName changes selection ndex ist filter removed TilterList TifterKey changeDict doltDict checkSystem fieldList FillinTheBlank actionBlock actionTaken Project proleciVVindovvs projectChangeSe projectTranscript projectHolder TextCollector entryStream Workspace 1localVariableDictionary Switch on onAction offAction Button OneOnSwitch connection SyntaxError class badText processHandle SystemTracer map refcts file holder vriteDic maxOop specialObjects TnitialProcess bank addr TekSystemTracer TekFileStatus TekSystemCall operationType operation DOln DOOut D1In D1Out ln A0ln A0 ufr erno TextSiyle fontArray TineGrid baseline alignment Tirstindent restindent
13. System User s 59 APPENDIX B SMALLTALK INTERNAL CHARACTER CODES Section 8 of the 4404 ATS Reference Manual contains a table of Event Manager Key Codes These raw key codes are mapped by the InpuiSensor class to an internal representation This means that shifted s has an internal value that is different from an unshifted s which is also different from a control s and a control shifted s The internal values are the ones used by the ParagraphEditor Alphanumeric Keys Table B 1 shows the Smalltalk Internal Character Code meanings for the main part of the keyboard the alphanumeric keys 60 4404 Smalltalk 80 System User s Smalltalk Internal Character Codes In this table control characters are represented by the standard two or three letter abbreviations given in ANSI X3 4 and ISO 646 Special symbols are represented by the four character codes assigned to those symbols in ISO 6937 These meanings of these four character codes are given in nearby notes Table B 1 Smalltalk Internal Character Codes North nu un iza Row 1 Keys Mode sm Unshifted 9 5 52 53 56 s Shifted 35 36 37 42 41 R Ctrl i m 143 128 130 a ii 180 2 z Ctri Shifted 249 223 Se 192 191 195 244 pal 127 A ii b i 105 m fe Fa 10 73 79 8 10 Ctrl i 150 15 ic 8 10 8 gt 2 20 214 202 mi Z Ctrl Shifted Row 3 Keysi Keys Mode TAR r m Unshi
14. by pressing another mouse button or typing at the keyboard 4 4404 Smalltalk 80 System User s A Smalltalk 80 System Overview You note immediately upon entering the Smalltalk 80 system that information is organized on the screen by being surrounded with rectangular boxes called windows Some windows contain Smalltalk code some contain pictures some contain text notes instructions warnings etc By experimenting with the mouse you observe that a number of different boxes with words appear on the screen These are the Smalltalk pop up menus The Smalltalk 80 system maintains within itself data that keeps track of which information is in what window and of course it knows where the arrowhead cursor is on the screen and what mouse button has just been pressed or released This data is constantly updated and is used to allow you to quickly select windows or the contents of windows and apply pop up menu commands to them Only the pop up menus appropriate to the placement of the mouse appear This helps focus your attention on the task at hand The Mouse You use the mouse to direct the major activities of the Smalltaik 80 system With the mouse you select an object and then select from a pop up menu what to do with the object You can select windows menu choices and text within windows The mouse has three buttons The left button the red button in the Addison Wesley Smalltalk books is used for selection Its primary use is fo
15. directory The copy name and rename options function as usual The new file option creates an empty file with the specified name and replaces the middle button menu with the normal middle button menu for files If you select the new directory option the specified name becomes a directory and the middle button menu is switched to the directory menu wrs When the get contents command is selected on a regular file the size is checked If a file is too large to fit in a String that is its size is greater than 65535 bytes a notifier appears with the message file too large to edit Printer Support The copy display command in the System Menu prompts for a file name and then copies the screen bitmap to that file This file is written in the same format as that of a Form The file can then be sent to the printer from the operating system To print a bitmap from a file called screen bm on a Tektronix 4644 printer type samplesiprinteribprint screen bm The bprint command defaults to double density which means that the print out looks half as wide as it should in relation to its height If you use the s option on the bprint command the aspect ratio looks much more like the real screen but the last few pixels on the right side of the screen are missing 46 4404 Smalltalk 80 System User s 4404 Smaiitaik Reference The print out menu option in the System Browser writes the code out to a file with a pp extension This code can
16. matches any number of characters and the pound sign matches a single character For example public st is acceptable but pu junkfile is not acceptable 4404 Smalltalk 80 System User s 45 4404 Smalltalk Reference If a name is selected in the second pane of a FileList a comment is displayed in the bottom pane The size and last modification date and time is displayed for existing files For directories a message states that the selected file is a directory If a new name is accepted in the first pane of a FileList the comment new file or directory is displayed If the selected name is a file the regular middle button menu is used in the second pane The first two items in this menu get contents and file in are not applicable for directories Thus if the selected name is a directory the menu is list contents spawn copy name rename remove The list contents selection lists the names of files within the directory in the bottom pane The spawn selection opens a new FileList on all the files within the directory This is similar to selecting spawn in one of the panes of a regular Browser The remove option removes the directory if it is empty If it is not a notifier appears saying that the directory cannot be removed because it is not empty If a new name is accepted in the first pane of a FileList and that name is selected in the second pane the middle button menu is copy name rename new file new
17. moves the cursor to the center of the visible viewport If the cursor is unlinked when the key is pressed it is re linked and the normal cursor is displayed A portion of the cursor form is normally constrained to be within the bounds of the virtual screen But depending upon the shape of the cursor within its 16 by 16 pixel cursor Form you may not always be able to see it File System Interface To open a previously existing file for reading or writing send the message oldFile with the file name as an argument to an instance of a FileDirectory such as f Disk oldFile timingData Executing this expression insures that the variable f is an instance of a FileStream on an existing file A notifier appears if the file does not exist To open a new file send the message newFile to an instance of a FileDirectory as in f Disk newFile testCases This guarantees that f is a FileStream on a new file named testCases If a file in the Disk directory previously exists with that name a confirmer tells you that the file already exists If you proceed the existing testCases file is renamed as testCases bak and a new testCases file is created The file message delays the opening of a file until a data transfer takes place f Disk file TestResulis If such an instance of a FileStream is sent the nextPut message and a file with that name already exists the file is automatically backed up vvith a bak extension and the data is wr
18. name of your image as the argument to the smalltalk command Invoking the Smalltalk 80 system for the First Time 1 Make sure all cables and power cords are connected and plugged in properly Refer to the 4404 AIS User s Manual if you are unsure of this Turn on the Mass Storage Unit MSU In the standard 4404 this contains the hard disk drive and one flexible disk drive The on off button is in the lower center front of the MSU Turn on the CPU Display Unit The square on off button for the CPU Display Unit is in the lower righthand corner You should hear hard disk activity and see the activity light flicker as the 4404 operating system is loaded into main memory The activity light is in the upper righthand corner of the MSU After a few seconds you should see this operating system prompt At the prompt type smalltalk followed by a carriage return You should hear more hard disk activity as the Smalltalk interpreter and the standard 4404 Smalltalk 80 virtual image are loaded into main memory The virtual image is a large file so be prepared to wait approximately forty seconds as it loads You should now see the 4404 screen displaying a familiar sight the Smalltalk System Browser window the System Transcript window etc of the Smalltalk 80 system Note that on the 4404 you see a portion of the entire Smalltalk 80 system screen You can look at other parts of the screen two ways If you move the mouse
19. newFileNamed filename st fileOutChanges in the System Workspace Modify the string representing the file name then select and execute this expression Executing this template records modifications that are contained in the ChangeSet for the current project A ChangeSet is an internal list of modifications one per project For instance you might create two projects for two distinct applications in your Smalltalk 80 image Since each project represents another screenful of information as well as another ChangeSet this is a convenient way to organize your work As long as changes relevant to each application are made in their respective projects the template mentioned above records modifications for that project Chapter 4 of the Goldberg book contains more information on projects Note that it is possible to modify the current ChangeSet See Chapter 23 of the Goldberg book for more information on the ChangeSet how it can be modified and how it can be used to recover from crashes Modifying your Changes File As you can see from the discussion above ChangeSets are a means of keeping a list of modifications that are recorded in your changes file The facility to condense a changes file is provided because much of the time modifications to a method go through several iterations before a final version is decided upon Each time the method is recompiled it is appended to the changes file even though only one version is referenced In the System
20. of the snapshot file It is stored as that name not snapshotim No command files are used On page 30 31 Section 2 1 Cursors In addition to the cursors shown there the 4404 Smalltalk 80 system has two more a major and minor compaction cursor These two cursors show up automatically when the Smalltalk 80 system is doing garbage collection related chores The minor compaction cursor has a leftward point arrow as part of its image The major compaction cursor is a box with a slanted line in it On page 43 Section 2 4 The System Menu The System Menu also has a hardcopy option copy display and a command that spawns a new shell in the 4404 operating system OS shell copy display copies the screen bitmap into a file that you specify or you can choose the default file name with a carriage return The entire bitmap of 1024 by 1024 pixels is copied to a file The file is relatively large so make sure you have enough room on your disk OS shell spawns a new shell in the 4404 operating system Thus you can set aside the Smalltalk 80 system while you do some things in the operating system When you are done return to the Smalitalk 80 system by typing the OS command exit On page 62 In the list of editing command keys substitute rubout for the delete key On page 179 The Browser s move menu item now prompts with the name of the currently selected class and protocol On page 209 210 The 4404 file system has been simplified which resul
21. protocol Controllers Coordinate systems Coordinates Screen See Screen coordinates Copy command Copy display command Copying text Copying the display Cursor Arrow Cursor Arrowhead Cursor Caret Cursors Compaction Cut command 64 14 15 20 4404 Smalltalk 80 System User s Debugging Demo files dir command Directories Enhancements to Smalltalk 80 system Equals Redefining Errata File descriptor File List window File Lists File system File system interface FileList commands Files Creation of Files Getting contents of Files Listing of Files Opening of Files Saving contents of Files Uploading See Uploading files Files VVriting of Filing in operation Form Forms Garbage collection Getting contents of files Hardware window Highlighting Image file problems Image file size Implementation See Smalltalk implementation Inheritance of classes Initialization directory Insertion of text Installing an image Invoking Smalltalk 80 system Joydisk Large files Left mouse button Left mouse button activity Line Feed key Listing files Logging in Managing a changes file Managing an image Manuals See 4404 Documentation Memory use Memory Virtual See Virtual Memory Menu commands 4404 Smalltalk 80 System User s 13 26 65 Index Menu items See Menu commands Menus Message selectors Messages Methods Definition of Middle mouse button Model
22. setting a context for execution Instances of subtask are created with a default environment the environment with which Smalltalk was invoked The method Subtask class copyEnvironment answers a copy of the default environment This copy is in dictionary format for easy modification The method Subtask environment assigns an environment to the Subtask instance which passes it to the executed program Here is an example of use of a modified environment which specifies that smalltalk is the current HOME directory 1 6 Subtask Support execProgram aCommand task env task Subtask fork aCommand then env Subtask copyEnvironment env at HOME put smalltalk task environment env task start isNil ifTrue self error Cannot execute aCommand task waitOn task abnormalTermination ifTrue self error Error from aCommand task release Signals Operating system signals colloquially referred to as interrupts can be intercepted ignored or set to a default action by using protocol in TekSystemCal11 class Usually the default action upon receipt of an interrupt is task termination See the 4404 Refence Manual the int command and epint system call for more details Sometimes it is desirable for the child task to intercept or modify its reaction to an interrupt Protocol to modify these reactions can be added to the block vvhich isan argument to the Subtask instance creation methods In our next exam
23. should turn on your 4404 and actually perform the steps on your own 4404 as you go through the tutorial In the Smalltalk 80 system there is no substitute for actual practice especially concerning the behavior of the mouse windows and menus The Goldberg book referred to in Section 1 is a very thorough introduction to the Smalltalk 80 system and you will find that the 4404 version of the Smalltalk 80 system is very nearly the same as that in the Goldberg book You can use the tutorial in this section to get a first acquaintance feel for the Smalltalk 80 system especially as it relates to the 4404 Then after you go through the tutorial you can turn to the Goldberg book to continue your introduction to the Smalltalk 80 system How to Get the Most Out of This Tutorial This tutorial is intended for programmers who are new to the Smalltalk 80 system If you are already acquainted with the Smalltalk 80 system on another machine you should turn to Section 4 It gets you quickly into the Smalltalk 80 system The Smalltalk 80 system depends on the 4404 electronics and the 4404 operating system Make sure that you are sufficiently familiar with these components before you go on to work with the Smalltalk 80 system You can become familiar with these components by reading through the 4404 AIS User s Manual Probably half an hour or so with the User s manual is sufficient Tutorial on the 4044 Smalitalk 80 System This tutorial assumes that
24. sian 32 About Model Vievv Controller 33 The Model View Controller Triad 222 33 View Displaying Protocol uzu dr rd YAR a da aa d s 33 How to Construct a Window 34 Controllers and Controller Protocol 35 A 1 S n l l 36 Viewports and Windows 38 4404 SMALLTALK REFERENCE 41 The Smalltalk 80 System in the 4404 OS Environment 41 Making System Cans sua YAR R aya e Ya daaa 41 Two System Call Examples 41 List of System Calls 42 4404 Primitive Metnos e 44 4404 Smalltalk 80 Virtual Image Enhancements 2 45 File Lists and Directory Browsers 222 45 Printet Support a becuse tins D LG spa sls 46 Title Changes 2 6 a A SUB n 48 Window Management al Ra o a eb ADD S s li 48 C rsof Center Eey m s a s ona 49 Bile system nterface a a LL 49 Framing Rectangular Regions AAA k s s bis 50 Workspace Variables oceans r bi 50 4404 and Smalltalk Version 2 User Interface Differences 50 Smalltalk File 52 The smalltalk Directory n ayib 52 The smalitalk system Dir
25. to as the parent task The child task is a copy of the parent task it shares memory and other resources with the parent task Since only one task can execute at a time cpu time is also shared initially in a predetermined fashion Common practice is for the spawned child task to perform some chore and then report back to the parent task After reporting the child task disappears This disappearance is known as the termination of the child task A parent may chose to relinquish use of the CPU until a subtask terminates It does this by an operation called waiting While waiting the parent task is blocked and cannot do anything else until the child task terminates The child task s chore is often accomplished by finding some other program to do the work The use of this other program is known as an exec operation for execute In an exec operation the original spawned task turns itself into the other program so the other program becomes the child task Often times a parent task may want to communicate with a child task Information can be sent to and from the child task by using pipes however each pipe can send information in only one direction If communication in two directions is desired two pipes must be used Pipes are similar to files with two critical differences Files can be reopened many times Pipes can only be opened once Once a pipe is closed it is gone Files can be reset and repositioned It is not pos
26. window to a file and get the contents of a file for use in the Smalltalk 80 system To do these things you need to open a File List window In opening a File List window the action that occurs is analogous to opening a workspace window Make this File List window about half the size of the visible screen You can put the window right over the System Browser and System Workspace windows if you like Do this now Move the arrow cursor to the gray background and choose the command file list from the middle mouse button menu Now move the window where you want it press and hold the left mouse button to anchor the upper left corner of the window move the lower right corner to where you want it and then release the button See Figure 5 Listing Files 31 To get a list of the smalltalk directory s files go to the top pane of the window just under the title box and type smalitalk The asterisk the wildcard character stands for all possible character combinations Now with the cursor still inside the top pane press the middle mouse button and choose accept You should see the middle pane of the window fill with the names of files in the smalitalk directory Use the scroll bar to find the file standardImage Select this file with the left mouse button In the bottom pane you should see a message about the size of the file and the time it was created It should look something like this 758256 bytes 23 September 1984 12 12 07
27. you are performing the steps on your 4404 in the order that they are given As you go through the tutorial and feel more confident about how the mouse windows and menus work feel free to try out operations similar to the ones described However in the beginning it is easy to miss some subtlety of mouse window menu interaction that could end up getting you lost in the Smalitalk 80 system So in the beginning an attitude of cautious exploration is urged 4404 Smalltalk 80 System User s 11 The 4404 Smalltalk 80 System A Tutorial You should allow around two hours to go through the tutorial Getting Into the Smallitalk 80 System 1 Make sure all cables and power cords are connected and plugged in properly Refer to the 4404 AIS User s Manual if you are unsure of this Turn on the Mass Storage Unit MSU In the standard 4404 this contains the hard disk drive and one flexible disk drive The on off button is in the lower center front of the MSU Turn on the CPU Display Unit The square on off button for the CPU Display Unit is in the lower righthand corner You should hear hard disk activity and see the activity light flicker as the 4404 operating system is loaded into main memory The activity light is in the upper righthand corner of the MSU After a few seconds you should see this operating system promptt 14 At the prompt type smalltalk followed by a carriage return You should hear more hard di
28. S 232 port 3 Login to the Unix system Use the xfer program with the gm option Note that the xfer program is an unsupported 4404 program supplied as a C language source file that you must compile and possibly edit to install on your Unix system You can transfer this xfer source file to your Unix system by Typing cat gt xfer c on your Unix system b Using the F1 key to return to the 4404 Typing list samples xfer cc gt devicomm on the 4404 afer c is in samples as the 4404 is shipped from the factory You should now have a copy of xfer c on your Unix system that you can compile and use to transfer files with error checking and carriage return to linefeed character translation Errors in the Addison Wesley Books The following is a list of errors in the Goldberg book imprint 1984 On page 83 in Figure 5 5 the syntax diagram for symbol needs a path out analogous to keyvvord 4404 Smalltalk 80 System User s 31 Programming in the Smalltalk 80 System On page 88 in the first paragraph sum count should be sum count On page 126 the icons for saving and retrieving a FormEditor form source should be reversed The following is a list of the errors in the Goldberg and Robson book which was reprinted with corrections May 1983 On pages 127 and 129 it should refer to printStringRadix instead of radix On page 202 the WriteStream instance protocol should list crtab and
29. TE K USERS Part No 070 5606 00 MANUAL Product Group 07 4404 ARTIFICIAL INTELLIGENCE SYSTEM INTRODUCTION TO THE SMALLTALK 80 SYSTEM Please Check at the Rear of this Manual for NOTES and CHANGE INFORMATION First Printing DEC 1984 Revised AUG 1985 Tektronix COMMITTED TO EXCELLENCE Copyright 2 1985 by Tektronix Inc Beaverton Oregon Printed in the United States of America All rights reserved Contents of this publication may not be reproduced in any form without permission of Tektronix Inc TEKTRONIX is a registered trademark of Tektronix Inc Smalitalk 80 is a trademark of Xerox Corp MANUAL REVISION STATUS PRODUCT 4404 Artificial Intelligence System Smallitalk 80 System This manual supports the following versions of this product Version T2 1 2 REV DATE DESCRIPTION DEC 1984 Original Issue AUG 1985 Addition of NOTES Section 4404 Smalitalk 80 System User s i CONTENTS 1 1 4404 Artificial Intelligence System Documentation 2 The Smalltalk 80 System Reference Books 22 3 A SMALLTALK 80 SYSTEM OVERVIEW 2 4 What is The Smalltalk 80 System 22 4 The User Interface Mouse Windows and Menus 4 ThE MODEL
30. Vievv Controlle Models Modem Mouse Mouse button states Mouse buttons Mouse manipulation Mouse operation Mouse Pad Multiple pane window Obiects Obiects Creation of Obiects Definition of Objects Internal structure of Obscured windows Operating system commands Operating system utilities Operation of 4404 Operation of Mouse Buttons Orange book OS shell command Panes See Window panes Paste command Pen example code Pen example display Personal image Pop up menus Pretty printed code Primitive methods Print it command Print out command Programming environment interactive Projects Put command Quiting Smalltalk 80 system Reading path README file Red book See Orange book Repaint command Restoring the display Return arrow key Right mouse button Right mouse button commands Right mouse button operation 66 4 7 16 5 6 9 7 5 2 25 33 Xu nrbi uau s DONERER 23 31 4404 Smalltalk 80 System User s Rubout key Saving Smalltalk work See Snapshot Making a Smalltalk Saving space Screen coordinates Screen size Scroll bar Scroll bar cursors Scrolling text Selecting an object Selecting objects Shapshot Smalltalk assignment operator Smalltalk block expression Smalltalk code Smalltalk code Example of Smalltalk code Execution of Smalltalk comments smalltalk file Smalltalk implementation Smalltalk local variables Smalltalk 80 language Smalltalk 80 language synt
31. Workspace under the heading Changes execution of the expression Smalltalk condenseChanges renames the original changes file to a backup name and creates a new changes file with duplicates and dolts removed Be sure to save your image after condensing changes so that the references to the new changes file are saved The section entitled Creating a New System Image beginning on page 478 of the Goldberg book discusses how and why to clone an image Since the format of Xerox and Tektronix images is different you must evaluate the expression TekSystemTracer writeClone to create a cloned image that can be brought up on the 4404 Circular garbage is reclaimed as a part of the normal garbage collection process so there is no need to clone an image to release these objects in a 4404 image You may still want to make a cloned image to release old Symbol table entries and since a clone image is 28 4404 Smalltalk 80 System User s Programming in the Smalltalk 80 System completely re organized to possibly obtain better locality of reference which means that the image might page less If You Cannot Bring Up Your Image After you have created your own image and saved some of your work in your own image file you may have created an image that does not load properly If this happens here are a few suggestions to help you track down the problem 1 Use the 4404 operating system command dir to check the size of your image file It should be a
32. a complete path name it is used as a path name relative to Disk For example if Disk is a FileDirectory on public sam and the image name mylmage is given the image is written to the file public sam mylmage Invoke the Smalltalk interpreter with the image name as a parameter to load the image saved in that file 4404 Smalltalk 80 System User s 27 Programming in the Smalltalk 80 System Hints Helps and Tips for Smalltalk Programmers The topics under this heading have been suggested by knowledgeable Smalltalk programmers Generally speaking these hints helps and tips are intended to make commonly performed tasks easier to do Managing Your Image and Changes Files Since the Smalltalk 80 system allows you complete freedom to personalize and change the Smalltalk programming environment to suit your needs there exists the possibility that you may make modifications that render your system inoperable If you are going to be programming at this level the following suggestions may help A good practice to follow is to alternate between two image files as you make changes to your system that is snapshot alternately between the two files This way you are always able to go back to a previous image Another recommended strategy is to record your modifications in an external file as Smalltalk source code This allows you to recreate all modifications to your image by filing in the source code To do this locate the template FileStream
33. al The Goldberg and Robson book is a formal explanation and description of the Smalltalk 80 language This includes not only the syntax of the language but also the classes of objects that make up the Smalltalk 80 virtual image This book also contains in part four a detailed discussion of the implementation of the virtual machine The Smalltalk 80 system virtual machine is usually implemented in a particular hardware environment as a combination of hardware registers and logic and assembly language or microcode instructions When you run the Smalltalk 80 system on the 4404 you first load the software part of the virtual machine called the interpreter and the virtual machine then loads the virtual image that you have specified in the command line If you expect to develop any Smalltalk applications you should study the Goldberg and Robson book This is the standard textbook describing the Smalltalk 80 language 4404 Smalltalk 80 System User s 3 SECTION 2 A SMALLTALK 80 SYSTEM OVERVIEW This section provides a brief look at the Smalltalk 80 system from the point of view of programmers and others who do not know the Smalltalk 80 system If you already know something about the Smalltalk 80 system you can skip directly to the 4404 Smalltalk 80 system tutorial in Section 3 If you are a proficient Smalltalk programmer you should skip directly to Section 4 You should refer to the Addison Wesley Smalltalk books mentioned in Section
34. alk 80 system into the file Here is how you do that A First open a File List vvindovv In the top pane type in the name of the file you want to put the text into Here type in junkfile Be sure to cut the asterisk or any other characters that might be in the top pane so that you have just the file name junkfile there Select the middle mouse button menu command accept You should see junkfile appear in the middle pane Now select junkfile in the middle pane with the left mouse button You should see the message new file or directory in the bottom pane If you do not try another file name until you can be sure you have a truly new file name Select the new file or directory message and cut it from the window Now go to the System Workspace window and select all of the text in that window by going to the very beginning of the text and clicking until you see all of the window text highlighted Do a copy command from the middle mouse button menu 4404 Smalltalk 80 System User s 4404 Smailtaik 80 System A Tutorial C Go back to the bottom pane of the File List window and do a paste from the middle mouse button menu The entire text from the System VVorkspace window should now be available to you in the File List window Use the scroll bar and verify that this did indeed occur D While you are still in the bottom pane of the File List window press the middle mouse button and look to the bottom of the pop up menu Choose t
35. alk 80 system on the 4404 and to give a brief introductory level look at the Smalltalk 80 system two textbooks published by Addison Wesley are highly recommended as supplementary material These books are Goldberg Adele Smalltalk 80 The Interactive Programming Environment Addison Wesley 1984 Called in this manual the Goldberg book but known among Smalltalk programmers as the orange book Goldberg Adele and David Robson Smalltalk 80 The Language and its Implementation Addison Wesley 1983 Called in this manual the Goldberg and Robson book but known among Smalltalk programmers as the blue book The Goldberg book is an extensive introduction to the Smalltalk 80 system There are many tutorial exercises that describe how to use the text editor how to make pictures how to find out about classes and messages how to program by modifying existing code how to create new classes of objects how to find and correct errors how to use the external file system to save changes you have made to the Smalltalk 80 image and so forth If your first acquaintance with the Smalltalk 80 system is on the 4404 you should read through Sections 2 and 3 in this manual and then proceed to the Goldberg book Use the 4404 and the Goldberg book to learn the Smalltalk 80 system Most tutorial exercises in the Goldberg book work on the 4404 exactly as they are described in the book The differences are noted in Section 5 of this manu
36. and GO messages would be different we hope The Smalltalk 80 language is especially suited to problems solved by simulation techniques Objects and Classes Since the Smalltalk 80 system and language is a completely object oriented language and system everything in the system can be thought of in terms of objects sending and receiving messages Even the user interface the windows contents of the windows the 6 4404 Smalltalk 80 System User s A Smalitalk 86 System Overview commands in the pop up menus the mouse button actions everything is an obiect or a message being sent or received Because the Smalltalk 80 language gives you access to this you can control almost every aspect of your personal Smalltalk 80 system Objects are programming constructs that have some private memory and a set of operations that they can perform So you can think of obyects as containing not only data structures but also as having access to subroutine like algorithms called methods The methods are executed when one object receives a message that names a particular method perhaps along with some arguments the receiving object needs to execute the invoked method You create an object by naming the class that describes it and by sending it an instance creation message usually the new message After this you can invoke the methods that the object understands that is those which are in its repertoire of methods by sending messages that deno
37. ar This appears when the Smalltalk 80 system is executing code Choose do it when you want to execute Smalltalk code 4404 Smalltalk 80 System User s The 4404 Smalltalk 80 System A Tutorial A good technique to use if you have a menu showing and have decided to choose none of the commands is to simply slide the cursor to the side out of the menu and release the button Clearing the Display 24 There are many times when the display gets cluttered with things that you are working with like the square spiral At any time you can restore the display with a middle mouse button pop up menu To see this menu you must be outside all windows that is the cursor must be positioned on the gray background Move the cursor to the gray background and press and hold the middle mouse button Observe that there are a number of menu choices for now go to the very top of the menu highlight restore display and then release You will see the entire display being rewritten Note that the square spiral disappeared it is indeed gone since it was not saved Altering and Running Some Smalltalk Code 25 By examining the Smalltalk Pen example method code you will probably be able to pick out certain constants that affect the shape and tone of the figure Use the left mouse button to highlight the 4 in the expression bic defaultNib 4 Now type 6 You should see the expression change to bic defauliNib 6 Once you are sure you have changed just t
38. ard error this mapping causes the write operations to be directed to the write side of the pipe Since the write end of the pipe has been redirected it is a good idea to close the write end with the message closeWrite In addition to closing redirected ends of the pipe in the child task unused ends of the pipe should be closed in both the parent and child tasks In this case the pipe read end is unused in the subtask and the pipe write end is unused in the parent task The net affect of all this closing and mapping is that the child task whose code is executed in the block closes the read side of the pipe because it is unused and closes the write side of the pipe because it has mapped the write side to standard output and standard error The parent task closes its unused end of the pipe which is the write side The parent task also creates a Smalltalk object for reading from the pipe an instance of PipeReadStream called inputSide InputSide inherits protocol from PipeStream and consequently ExternalStream Although other methods may be used to read from the pipe here the method contentsOfEntireFile is used to read all the data from the pipe and the pipe is closed after use The following method found in execSystemUtility withArgs TekSystemCall class in addition to havinf the same functionality as the method immediately above also has error checking and passes arguments to the executable program aCommand Subtask Support execSyste
39. ars here for your convenience You can generate the same list by selecting the category Kernel Object and the class Object in the System Browser and then by selecting hierarchy in the pop up menu 4404 Smalltalk 80 System User s 53 Smalltalk Classes List Object Behavior superclass methodDict format subclasses ClassDescription instanceVariables organization Class nam classPool sharedPools all the Metaclasses Metaclass thisClass M taclassForMultplelnheritance otherSuperclasses Benchmark dummy verboseTranseript reporting TeportStream fromList BinaryChoice trueAction TalseAction actionTaken destForm sourceForm TalftoneForm combinationRule destX destY width height sourceX sourceY clipX clipY clipWidth clipHeight CharacterScanner lastIndex stopConditions tex textStyle TeftMargin rightMargin font tine runStopindex spaceCoun spaceWidth outputMedium CharacterBlockScanner characterPoint characterindex TastCharacter lastCharacterExtent TastSpaceOrTabExteri nextLeftMargin CompositionScanner spaceX spacelndex DisplayScanner 1TineY Pen frame location direction penDow Boolean False True
40. ask Acceptable values range from 0 to 25 zero being the highest and 25 being the lowest aPriority lt 0 aPriority gt 25 ifTrue self error Unacceptable priority value priority aPriority The Smalltalk parent task initially has a priority of 10 If the child task is created with a higher priority than the parent task it has a potential of taking control of the CPU A higher priority task will not relinquish the CPU to a lower priority task unless the higher one is blocked or terminates The next example increases the child task s priority and uses two pipes for two way communication It is known that the child task in this case will be blocked while waiting for input so the parent task will have a chance to run The class ShellInterface creates a view that communicates with a shell bin script interactively Note that this class is not contained inthe standardImage but defined in the file smalltalk fileIn Examples Subtasking After an instance of this class is created it is initialized with the following method Application Note 1 9 Subtask Support initialize pipeln pipeOut sysCall command command result asText pipeln Pipe new pipeOut Pipe new shellTask Subtask fork bin script then FileStream releaseStdRefs pipeIn mapWriteTo 1 pipeln mapWriteTo 2 pipeln closeVrite pipeln closeRead pipetut mapReadTo 0 pipetut closeRead pipeOut closeVritel shellTask enha
41. ask mainly communication and signal processing and exec ing the program If the exec fails terminate the child task The child task will inherit the priority of the Smalltalk task forker execer task forker TekSystemCall vfork environment isNil ifTrue lexecer TekSystemCall exec program with args ifFalse lexecer TekSystemCall execve program withArgs args withEnv environment forker value initBlock value self priority notNil ifTrue TekSystemCall setpr priority value FileStream closeExternalReferences execer invoke ifFalse TekSystemCall term value self taskId nil mill self taskId execer DOOut ScheduledSubtasks add self self criticalSection self status frunningl Subtasks are run from Smalltalk by making two essential system calls The vfork system call forker creates a child task which shares memory with the parent task The exec execve system call execer transforms the child task so it is no longer running Smalltalk but is executing the specified binary file program Execer is created with either the exec system call exec with or with the execve system call execve withArgs withEnv depending on whether an environment is passed to the binary program Before the exec execve invocation execer value communications and signals must be set up When an instance of Subtask is created potentially a block is passed as an argument containing code for setting up communications an
42. ax Smalltalk 80 system Definition of Snapshot Snapshot Making a Smalltalk Spawning a shell from Smalltalk 80 system Standard configuration standardChanges file standardI mage file StandardImage file standardSources file Subclasses Subviews Summary of tutorial Super classes Syntax See Smalltalk 80 language syntax System Browser window System call examples System calls System Change Set System Transcript window System Transcript Function of System Workspace window System Workspace Function of Tektronix 4644 printer Tempiate Template code Text Text in Smalltalk 80 system Titles See Window Titles Transferring files See Uploading files 4404 Smalltalk 80 System User s Index Un ocodka hn ne s 7 16 19 20 8 25 2 3 8 3 6 7 5 15 26 5 15 26 27 28 16 14 67 Index Turning on the 4404 Tutorial Tutorial Summary of See Summary of tutorial Undo command Uploading files Utilities See Operation system utilities Variables Local Variables Workspace View code example View protocol Viewport Viewports Views _ Virtual image Virtual memory Wildcard characters Window code example Window commands Window management Window panes Window Titles Windows Windows Obscured See Obscured windows Windows System created Wire List example Workspace window Xfer program primitive copy command cut command do it command Form expression Pen
43. bout the same size as the standard image file The standard image file standardImage is approximately 1500 blocks in size 2 If your image file seems to be about the right size check to make sure that you have enough free memory on the disk for the operating system to function Remember that the operating system uses part of the winchester disk space as main memory because it uses a virtual memory paging scheme to extend main memory Use the operating system command free dev disk to find out how much memoiy is left on the disk To be safe you should have at least 1 megabyte about 2000 blocks of memory left on the disk Enhancements to the System Workspace The following enhancements have been made to the System Workspace See p 503 509 of the Goldberg book for explanations of the other expressions in the System Workspace Create File System Disk FileDirectory directoryNamed public Make the Smalltalk home directory an absolute path in this case set it to the public directory Disk FileDirectory currentDirectory Make the home directory float to the directory in which the Smalltalk 80 system was invoked This is the value for Disk in the default standard image If for example you are in the public directory when you bring the standardlmage up Disk is set to public and all files are written to this directory unless a complete path name is explicitly specified If you are in the bin directory when you bring up the
44. child or a program interrupt write fileDescriptor buffer buff nbytes numberOfBytes Writes the contents of the buffer to a file 4404 Primitive Methods All primitive methods described in the Goldberg and Robson book in Chapter 29 are implemented in the 4404 Smalltalk 80 system These include all the optional standard primitive methods In addition the 4404 Smalltalk interpreter implements a number of implementation dependent primitives They are listed here along with a brief description of each one 44 4404 Smalltalk 80 System User s 4404 Smalltalk Reference Primitive 129 namedSnapshot This is a primitive method in class SystemDictionary Its argument is a file name Invocation of this primitive causes a snapshot of the currently executing virtual image to be written to the file If the call is successful the primitive returns nil or self otherwise it fails If the image was just written the returned value is nil If it is being restored the returned value is self Primitive 130 primitiveIncrementSP This is a primitive method in class ContextPart It adds one to the stack pointer field of the receiving context and stores nil into the new top of stack element This primitive and primitive 131 are the only acceptable ways to explicitly modify a context s stack pointer Primitive 131 primitiveDecrementSP This is a primitive method in class ContextPart It subtracts one from the stack pointer field of the receiving c
45. choose the restore display command from the System Menu each view goes through this sequence of messages displayBorder display View displaySubViews Each kind of view knows how to display the special kind of model information that it is suited to You can use the System Browser to explore how different kinds of views display themselves 4404 Smalltalk 80 System User s 33 Programming in the Smalitalk 80 System aController aVievv AM A Fi aModel aController A aVievv Figure 6 Double Window With Two Model View Controllers How to Construct a Window Here is some Smalltalk 80 language pseudocode to give you an idea of how to construct a side by side two paned window leftSubView NewKindOfView new model aNevvKindOfVievv bordervvidth 2 insideColor Form white rightSubView NewKindOfView new model aNewKindOfView borderWidth left 0 right 2 top 2 bottom 2 insideColor Form white topView StandardSystemView new label NewKindOfView Window addSubView leftSubView addSubView rightSubView toRightOf leftSubView topView controller open 34 4404 Smalltalk 80 System User s Programming in the Smalltalk 80 System The pseudocode assumes of course that you have already created NewKindOfView by creating a subclass of the class Vievv or one of the many kinds of vievvs that are part of the standard system such as ListView WorkspaceView and so forth Note that the pseud
46. class names pane This one has the two boxes at the bottom with instance and class make sure instance is highlighted by clicking with the left button on instance Select the class name Integer Now the next pane to the right fills with a list of message categories and the bottom pane template code changes again Select factorization and divisibiliy in the message category pane Again the next pane over the message selector pane fills with a list of expressions These are actual Smalltalk code message selectors You will find these throughout Smalltalk code as you examine the code in the system Finally go to the rightmost pane and select factorial asterisk This symbol is the message selector for factorial You now see in the bottom pane the actual Smalltalk code that is executed if you compile and run a Smalltalk expression such as 4 factorial After you have examined the code to your satisfaction try going back to the message selector pane and 4404 Smalltalk 80 System User s The 4404 Smalltalk 80 System A Tutorial Disk FileDirectory curren Yaxt Brew ser Collections Unordered Collections Sequencea 9 P instance creation Collections Text Point examples gt Collections Arrayed Quadrangle Collections Streams Rectangle Collections Support Jara pes Primitives Graphics Display Obje Graphics Paths Graphics Views r elass example Draws a spiral in gray with a pen that is 4 pixels wide bic
47. creates a data structure for making a system call and the method value causes the link system call to be executed and detects errors rename aFileName as newFileName Rename the file named aFileName to have the name newFileName Create an error if aFileName does not exist but not if newFileName exists self unlink newFileName valuelfError self link aFileName to newFileName value self unlink aFileName value Find the next example by selecting open mode in the message selectors pane of the System Browsers and opening a senders of open mode window Choose TekSystemCall class open to see the following code open aString Open the file named aString Answer a readWrite fileDescriptor for the file sysCall sysCall self open aString mode 2 sysCall value tsysCall DOout Note that the the ASCII up arrow is the return arrow in Smalltalk code aSiring is a file name and mode 2 means to open the file for both reading and writing These arguments correspond to the arguments described in the 4404 AIS Reference Manual in the Section 6 System Calls Look up the system call named open Note also that this method returns the file descriptor in register D corresponding to the documented open system call interface List of System Calls The following is a list of operating system calls accessible from the Smalltalk 80 system You can find these in the System Browser by choosing the Files Support category
48. creen and puts it in a hidden buffer do it This executes runs currently selected code print it This executes currently selected code like do it but it also prints the result on the screen print it is an appropriate command for the Smalltalk expression 3 4 whose result is of course 7 You see 7 displayed on the screen immediately after the 3 4 expression The Smalltalk 80 Language Smalltalk is an object oriented language Things happen in a Smalltalk 80 system because objects are sent messages Objects are system components which are described by their corresponding class Each class contains a description of its object implementation This description is used to create new instances of this ciass Messages are requests for an object to carry out one of its operations When you create an instance of a class you create an object that responds to a definite set of messages For example suppose you need to simulate the behavior of traffic in a town You might create classes of objects that represent traffic lights cars streets and people A traffic light would have three states through which it would cycle Cars would stop and go along streets People would cross streets and stop at traffic lights etc In the Smalltalk 80 system you would design each object so that it responded to appropriate messages For example people objects and car objects might both respond to STOP and GO messages but their response to STOP
49. crtab instead of erTab and crTab On page 289 it says to add the method to the instance creation protocol of class Class but it should be added to the instance protocol named subclass creation On pages 333 and 338 it refers to the class Bitmap This class has been renamed VVordArray On page 399 it shovvs the vvait cursor as three dots instead of the current hourglass shape The message to Cursor for the crosshair is crossHair instead of crosshair Multiple Inheritance of Classes The Smalltalk 80 system supports multiple inheritance of classes which allows objects to inherit methods from two or more super classes Ordinary subclassing only allows inheritance from a single class For an example of how to use multiple inheritance go to the System Browser and choose Collections Streams and Stream Then choose hierarchy from the middle mouse button In the bottom pane you see this hierarchy Stream PositionableStream collection position readLimit ReadStream WriteStream vriteLimit ReadWriteStream Instead of using this single inheritance scheme ReadWriteStream could be a subclass of both ReadStream and WriteStream Make the class NewReadWriteStream be a subclass of both by entering the following code in place of the normal class template for ReadWriteStream Class named NewReadWriteStream superclasses ReadStream VVriteStream instanceVariableNames classVariableNames cate
50. cursor to the edge of the screen the screen does a hardware scroll and brings into view previously hidden parts of the entire screen Alternatively you can scroll the screen with the joydisk the octagonal shaped disk in the upper lefthand corner of the keyboard Note that with the joydisk you can pan the cursor off the visible display Press the Cursor Center Key F12 to bring the cursor to the center of the visible display if you need to If the sequence of events described in this procedure does not occur as you expect you should refer to the 4404 AIS User s Manual 26 4404 Smalltalk 80 System User s Programming in the Smalltalk 80 System Installing Your Own Image After you have had enough experience with the editor and menus to feel comfortable editing and executing Smalltalk code you may wish to install your own personal image To do this follow these steps 1 Establish your Disk directory Disk is a global variable representing an instance of a FileDirectory Filenames that do not begin with a 7 are assumed to be relative to this directory For instance doing a file out in a Browser creates a file in the Disk directory You should have write access to this directory Use the first template in the System Workspace under the Create File System heading to set up your Disk directory Edit the template select the entire line and then execute it with the middle button menu item do it For example your Disk might b
51. d Smalltalk expression at the end of example code is a common way to show how to execute the example code This brief look at some Smalltalk code shows you how the primary programming constructs objects and methods have been implemented in a programming language Pen is the name of a class that denotes a certain kind of object An instance of Pen understands a definite set of messages and these messages denote methods think of them as subroutines that accomplish appropriate tasks for Pen objects Note that all the individual terms denote either objects or messages The Smalltalk 80 system 15 completely objected oriented Sometimes this seems odd when you are asked to think of 4404 Smalltalk 80 System User s 9 A Smallitalk 80 System Overview 3 4 as send the object 3 the message 4 On the other hand bic defaultNib 4 meaning send the Pen object bic the message to make its point four pixels wide seems quite understandable and natural on first meeting Just remember that everything you deal with in the Smalltalk 80 system is an object 10 4404 Smalltalk 80 System User s SECTION 3 THE 4404 SMALLTALK 80 SYSTEM A TUTORIAL This section is intended for the first time user of the Smalltalk 80 system on the 4404 Its purpose is to get you into the Smalltalk 80 system show you some commonly used features and exit you back to the 4404 operating system The information in this section is presented as a tutorial which means that you
52. d signals in the child task This block was stored in the instance variable initBlock which is evaluated at this point Priorities are also assigned at this time and files belonging to the parent task Smalltalk are closed with the expression FileStream closeExternalReferences After the child task has been spawned and control returns to the parent the task identification number is recorded by the parent task self taskId execer DOOut the child task is added to the list of managed subtasks ScheduledSubtasks add self and its status is recorded If the execer Subtask Support call fails the child task terminates itself with the term method and the parent task returns nil At the vfork invocation forker value control of the Smalltalk virtual machine transfers to the child task The child task continues executing with no access to the keyboard or the mouse until the execer call is invoked This means that the code from forker value to execer invoke is only executed by the child task In addition TekSystemCall term 0 value is executed by the child task to terminate itself if the execer call fails Then the parent task resumes control and executes the statements self taskId nil fnil to indicate failure of the execer call The next statements starting with self taskId execer DOOut are also executed by the parent task but only if the execer call was successful Whenever the child task is blocked or the child task terminat
53. d with the Smalltalk 80 system Section 2 presents the main features of the programming environment language and user interface Section 3 This is a tutorial for the Smalltalk 80 system on the 4404 You learn how to bring up the Smalltalk 80 system from a powered off 4404 You learn how the mouse interacts with the windowing user interface You learn how to open up a workspace window use the editor to type in some simple Smalltalk code and compile and execute the code You also learn how to find information about the over 200 Smalltalk classes and their messages Section 4 Here you learn how to bring up the Smalltalk 80 system quickly You are provided with hints and tips about programming You learn the basic ideas behind Model View Controller an important part of the Smalltalk 80 system that you need to understand to design and write sophisticated Smalltalk applications Section 5 This section contains the implementation aspects of the 4404 version of the Smalltalk 80 system How the Smalltalk 80 system and the 4404 operating system interact is described Also Smalltalk 80 virtual image enhancements are presented And finally this section discusses the few differences between the Smalltalk 80 System Version 2 as it is described in the Addison Wesley books and the 4404 version Appendices In Appendix A you find a list of Smalltalk classes In Appendix B there are tables describing Smalltalk internal character codes Th
54. does not appear in this example bic mask Form gray 8 4404 Smalltalk 80 System User s A Smalltalk 80 System Overview gray is a message that is sent to the object Form Note that Form is capitalized A Form object is a set of bits that represents a rectangular region for display on the Smalltalk screen Since the Smalltalk 80 system supports a bitmap in which pixels are either black or white shades of gray are simulated by patterns of black and white pixels So Form gray creates a gray halftone image The mask message specifies that a gray image be the mask for the Pen object bic An instance of Pen understands the method denoted by mask because mask is already in its repertoire of methods bic defaultNib 4 Here 4 is an object that the message defaultNib can take as an argument bic which is an instance of Pen understands the message defaultNib 4 This message tells bic to make its pen point four pixels in diameter bic combinationRule Form under combinationRule is a message that takes an integer as an argument In the Smalltalk 80 system integers are objects so the expression following combinationRule should evaluate to an integer The expression Form under does indeed evaluate to an integer In fact it returns the integer 7 This is interpreted by bic as one of the sixteen combination rule modes that the drawing primitive BitBlt understands BitBlt performs all drawing operations that are requested of Form objects
55. e Disk FileDirectory directoryNamed public The directory should previously exist Install your changes file Find the line in the System Workspace several lines down from the expression you executed to initialize your Disk directory that begins with SourceFiles at 2 put Edit the next line so that it looks something like this FileStream oldFileNamed changes Each user should have a separate changes file You may use a different name for your changes file The first time you execute these two lines with a do it command a notifier should tell you that the file does not exist Proceed so that the file is created If you do not get a notifier someone else has already created a file with this name You should choose a new name for your changes file and re execute these two lines Every time you execute a do it or accept a new method that action is recorded in your changes file Save your templates Use the middle mouse button accept command inside the System Workspace This saves the contents so that all new System Workspaces opened from the System Menu reflect an up to date version of the contents of the System Workspace Make a snapshot Use the System Menu to make a snapshot You then are prompted for the name of a file that receives your personal copy of the Smalltalk 80 virtual image If you type a path name that begins with a slash the image is saved in a file with this complete path name If the name is not
56. e 4404 Artificial Intelligence System Documentation In addition to this manual the following documentation comes with the standard 4404 4404 Artificial Intelligence System User s Manual This manual contains what you need to know to operate the 4404 controls It also has an introduction to the 4404 operating system for the first time user 4404 Artificial Intelligence System Reference Manual Here you find detailed information about all the operating system commands system calls and utilities The 4404 s hardware is discussed here from the programmer s point of view And finaily you find documentation for the 68000 assembler and linker the C language compiler the text editor EDIT and the terminal emulator This manual assumes that you have gone through the 4404 AIS User s Manual The user s manual gives a good introduction to the 4404 and the operating system that the Smalltalk 80 system is built on top of Take the time to become familiar with the 4404 controls and the operating system This requires only about an hour or so especially if you are familiar with the UNIX operating system or a UNIX like operating system The other software options have their own documentation which you receive when you order these options UNIX is a Trademark of Bell Laboratories 2 4404 Smalltalk 80 System User s ntroduction The Smalltalk 80 System Reference Books Since the purposes of this manual are to document the Smallt
57. ectory 52 Additional source 52 52 SMALLTALK CLASSES LIST a aa as a s y 53 SMALLTALK INTERNAL CHARACTER CODES 5222 60 iii 4404 Smalltalk 80 System User s Figure k OO QO RN Q amp DH ND m ILLUSTRATIONS Description Initial Screen of Standard Image System Workspace Window System Browser Window Workspace Window File List Window Double Window With Two Model View Controllers Hierarchy of Model View Controllers ScheduledControllers for Three Model View Controllers User View of Wire List Example Window Viewport Relationship Composition of Multiple Window Viewport Transformation 4404 Smalltalk 80 System User s iv SECTION 1 INTRODUCTION Welcome to the world of the Smalltalk 80f system Your 4404 Artificial Intelligence System called the 4404 in this manual supports the Smalltalk 80 System Version 2 release of the Smalltalk 80 language and environment With the 4404 and the Smalltalk 80 language and its environment you have all you need to explore Smailtalk programming and develop Smalltalk applications code The 4404 can also serve as the delivery vehicle for the applications developed on it This manual has two primary goals it instructs you in the invocation of the Smalltalk 80 system on the 4404 no matter what your background in the Smalltalk 80 system i
58. electorSet TitindSet 1192 sourceRanges TastTempPos LeafNode key code LiteralNode SelectorNode VariableNode name isArg MessageNode receiver selector precedence special argumente sizes pe MethodNode selectorOrFals precedence arguments block literals primitive encoder temporaries ReturnNode expr pc ParseStack position Tengih Point xX Yy l PopUpMenu 1abelSiring font TineArray frame form marker selection ActionMenu selectors ProcessHandle process controller interrupted TesumeContext proceedValue ProcessorScheduler quiescentProcessLists activeProcess Rectangle origin corner CharacterBlock siringindex character Quadrangle borderVVidih borderColor insideColor 4404 Smalltalk 80 System User s 57 Smalltalk Classes List RemoteString sourceFileNumber TilePositionHi TilePositionLo Scanner source mark aheadChar token TokenType currentComment buffer typeTable ChangeScanner chunkString Parser here hereType TereMark PprevToken prevMark encoder requestor parseNode TailBlock TastTempMark correctionDelta SharedQueue contentsArray readPosition writePosition accessProtect readSynch Siream 0
59. error Cannot fork shell Interrupt action is modified in both the parent and child tasks by using the method setInterrupt to which returns the previous action for that interrupt First the parent interrupt actions are saved in temporary variables while setting interrupt action to 1 which means to ignore the interrupt In the subtask these same interrupts are reset to the default action by making the interrupt action After the subtask has completed the interrupts in the parent task are set back to their original values This subtask runs by using the protocol previously described but the parent task waits for the child task to terminate by using the method absoluteWait This method actually shuts down the Smalltalk parent task so it receives no time slice from the operating system scheduler This strategy of waiting makes the subtask more efficient because the parent task cannot steal any processing power However Smalltalk cannot run until the child task has terminated AbsoluteWait is not appropriate for any subtask that depends on the Smalltalk user interface Subtask Support Priorities and Two Way Communication Subtasks can be made to run more efficiently by changing their priorities Sending the message priority to an instance of Subtask modifies the invocation of a subtask so that it runs at the designated priority Here is the definition of the method Subtask priority priority aPriority Set the priority of the subt
60. es control reverts back to the parent task The parent task initially resumes control in the state left by the child task before the forker invocation Application Note 1 13
61. es a summary of what the method does Comments are enclosed in double quotation marks and may be interspersed anywhere in the code bic Two vertical bars enclose the declaration of local variables You can have more than one variable if necessary each separated by a space from the next one Here bic is the only local variable in the method It is in good style to begin local identifiers with a lower case letter Note that there is a blank line immediately preceding this line The blank line separating the opening comment and the temporary variable declaration is also a matter of good Smalltalk style bic Pen new Pen is an object that behaves like a plotter pen It understands direction up down move and so forth Note that Pen begins with a capital letter All class names in Smalitalk begin with a capital letter new is the name of a message that is sent to Pen and it tells Pen to create an instance of itself This newly created instance of Pen is then assigned by the left arrow assignment operator to the local variable bic Note that the expression ends with a period This separates well formed expressions from one another The left arrow assignment operator is a non ASCII character that gets mapped to the underscore character when a translation is done from Smalltalk code to pure ASCII characters There is only one other special non ASCII symbol in the Smalltalk 80 system the upward pointing return arrow which
62. eter is called bin smalltalk For more information about the contents of the sources image and changes files see the Goldberg book pages 457 458 The smalltalk system Directory The smalltalk system directory contains the following system files standardSources This contains the standard source code for each of the compiled methods in the standard image standardChanges Initially empty this file is the default changes file corresponding to the standardImage This file may grow each time the standardImage is used 6 initialization This directory contains files that are needed for class initializations Additional source code The smalltalk fileIn directory contains additional source methods which may be filed into the image A README file documents this code This code is not supported and is distributed on an as is basis Demo material The smalltalkidemo directory contains an image changes file and other source files which may be used for demonstration purposes The code in these files is not necessarily fully debugged and is not supported You can delete these files to save disk space demolmage This is an image with interesting applications not considered essential for the standardI mage demoChanges The changes file for the demolmage 52 4404 Smalltalk 80 System User s APPENDIX A SMALLTALK CLASSES LIST This hierarchical list of all the classes in the 4404 version of the Smalltalk 80 system appe
63. example print it command 68 4 33 38 4404 Smalltalk 80 System User s Application Note SUBTASK SUPPORT AND MANAGEMENT Support for subtasks created by the operating system is available in the Smalltalk 80 system Although Smalltalk has its own processes Smalltalk can also create and communicate with subtasks created by the operating system Smalltalk processes provide independent paths ot control within Smalltalk All Smalltalk processes share access to the same set of objects Operating system subtasks provide access to other executable programs These subtasks are useful for running OS utilities and commands as well as communicating with applications and programs written in other languages Subtasks can be executed without leaving the Smalltalk environment Protocol supporting subtasks is found in the classes Subtask Pipe PipeStream and its subclasses The objective of this support is to make the job of creating running and communicating with the subtasks straightforward Interfaces to OS signals program parameters environment variables and subtask priorities are also supported OVERVIEW OF SUBTASKS AND PIPES The operating system on the 4404 supports multi tasking With Smalltalk s interface to the operating system via system calls it is possible for Smalltalk to utilize this facility Multi tasking is achieved by spawning new tasks A newly spawned task is cailed a child task or a subtask The original task is referred
64. fted Shifted Unshifted 115 Shifted s yi 83 a a a F z 5 Ctrl 9 11195141 6 7 18 ee 1911 122 138 b Ctrl Shifted 9 212 211 196 226 243 229 200 zu 219 Row 4 Keys Mode Z i gt 46 62 18 mi 230 ve ji 233 a Row 5 55 Mode Unshifted Shifted Ctrl Ctrl Shifted Notes an low line SP10 hyphen or minus sign B 1 Numeric Pad Keys The numeric pad is located to the right of the main set of alphanumeric keys Table B 2 Smalltalk Internal Character Codes al 20 board Key Pad Name Mode Unshifted 46 44 45 27 Shifted 175 177 176 178 Ctr 255 255 255 255 Ctrl Shifted 255 255 255 4404 Smalltalk 80 System User s 61 Smalltalk Internal Character Codes B 2 Toydisk Keys The joydisk is located to the upper left of the main set of alphanumeric keys Table B 3 Standard North American Keyboard Joydisk Key Name Up Down Right Left 255 255 255 255 Unshifted 255 255 Shifted 255 255 Ctrl 255 255 255 255 Ctrl Shifted 255 255 255 255 B3 Function Keys The function keys F1 F12 are grouped in three groups of four keys and are located in a row above both the alphanumeric keys and the numeric key pad Table B 4 Smalltalk Internal Character Codes Standard North American Keyboard Function Key Name Fi F2 Mode oad Unshifted 151 152 Shifted 163 164 Ctrl Ctrl Shifted Function Key Name
65. g for a specified number of seconds or just waiting until a mouse button has been pressed The last expression would allow you to try dangerous code or print extensive debugging information only part of the time since the block expression is executed only when the left shift button is depressed Redefining Since is such a fundamental operation you should be very careful if you redefine it You may also need to redefine hash at the same time see Goldberg and Robson p 96 Uploading Files to Another Computer System You may want to upload files from your Smalltalk 80 system to another computer system The UNIX operating system has been chosen here for the procedure but most of the steps apply to other operating systems Follow this basic procedure 1 If you wish to save text from a Smalltalk workspace create a new file using a File List window and copy the text from the workspace into the bottom pane Choose the menu item put to write out the contents of the File List window into the new file You might also file out code from a Browser 2 Exit the Smalltalk 80 system with a System Menu OS shell choice Establish an RS 232 connection with the Unix computer and the 4404 AI System by physically connecting an RS 232 cable and doing whatever you must call up on a modem use a TIA device etc to communicate to the Unix system Type the 4404 operating system command remote to establish communication between the 4404 OS and the R
66. gory Collections Streams VVhen you accept this code the system generates conflicting inherited methods messages in the System Transcript because in the case of identical messages it does not know which methods from ReadStream or WriteStream it should inherit You can use the Browser to eliminate the sources of these errors by specifically indicating which of the conflicting methods to use or by removing the sources of conflict 32 4404 Smalltalk 80 System User s Programming in the Smalltalk 80 System For more information refer to the paper by Alan H Borning and Daniel H H Ingalls Multiple Inheritance in Smalltalk 80 pp 234 237 Proceedings of the National Conference on Artificial Intelligence Pittsburgh PA 1982 About Model View Controller This section presents a brief conceptual overview to the topic of models views and controllers An understanding of models views and controllers allows you to create Smalltalk applications that make sophisticated use of windows A model is the data that you want to represent on the Smalltalk screen The model may be a string of text an array of coordinates representing a waveform a bitmap representing a digitized picture etc The model contains no information about how to display itself This is the job of a view A view is the mechanism that a model uses to display itself in windows on the Smalltalk screen A view knows how to display the information in a model There are
67. hArgs OrderedCollection with fileName with flags The next example executes a shell with a c option The c option tells the shell to read the rest of the arguments as a command to itself The effect is a directory listing with the shell providing wildcard expansion pattern smalltalk de nameList TekSystemCall execSystemUtility bin shell withArgs OrderedCollection with c with bin dir s pattern Besides taking advantage of the shell s wildcard expansions you can also use aliases which are stored in the shellhistory file See the 4404 Reference Manual the shell command for more details TekSystemCall execSystemUtility bin shell withArgs OrderedCollection with tc with df where df is an alias for free dev disk To execute a program with no arguments substitute an empty OrderedCollection for the second argument TekSystemCall execSystemUtility bin date vithArgs rderedCollection nev Environment Variables The Smalitalk 80 system s interface to subtasks also supports environment variables See the 4404 Reference Manual for more details In general when a program is invoked the operating system passes arguments and environment variables to the program Standard environment variables include HOME a home directory specification and PATH a search path specification Environments are a way to pass information by name This can be viewed as
68. hat the text moves up one or more lines for each press and release depending on whether you are at the top middle or bottom of the scroll box The farther down you go in the scroll box the greater the number of lines you scroll at a time The downward pointing half arrow works analogously Now find the horizontally pointing arrow press and hold the left mouse button and move the mouse up or down Observe that the gray scroll bar follows your motion Release the left mouse button with the scroll bar positioned at the bottom of its box You are now looking at the end of the text in the window Now move the scroll bar to the top of the box You are now of course looking at the beginning of the text in the window Play with the scroll bar cursors until you feel comfortable with their operation How to Find Out About Classes and Messages 18 At this point you have learned the basic operation of the mouse and left mouse button You can now explore the middle and right mouse button operation and learn something about the System Browser at the same time Move the arrow cursor into the System Browser window and click press and immediately release the left mouse button You have of course just activated the System Browser See Figure 3 Note that it has five major panes four small ones at the top and one large one below these four As you can see the leftmost small pane has some class category names in it Move the arrow cursor into this small
69. hat you have learned here and extend your knowledge of the Smalltalk 80 system by going directly to the Addison Wesley Smalltalk books See Section 1 for more information about these books Please note that the last two sections of this manual are meant mainly for the person who has already absorbed what is in the Addison Wesley books 24 4404 Smalltalk 80 System User s SECTION 4 PROGRAMMING IN THE SMALLTALK 80 SYSTEM This section is intended for the experienced Smalitalk programmer That is it is assumed that you have actually done some Smalltalk programming on another machine If you have not you should probably read through Sections 2 and 3 first the Addison Wesley books next and then come back to this section This section presents three topics First it tells you how to get into the Smalltalk 80 system quickly Second it presents a number of programmer hints helps tips etc to make your life as a Smalltalk programmer easier And third it explores a topic that is not extensively treated in the Addison Wesley Goldberg or Goldberg and Robson books This is Model View Controller Some understanding of this topic is necessary to write Smalltalk applications involving the window user interface Getting into the Smalitalk 80 System on the 4404 The Smalltalk 80 system depends on the 4404 machine itself and the 4404 operating system Make sure that you are sufficiently familiar with these components before you go on to
70. he command puf You should hear some disk activity as the Smalltalk 80 system outputs the contents of the File List window into the file called junkfile Now to verify that the file did get written go to the middle pane and deselect junkfile by clicking on it Now select junkfile again and the bottom pane of the File List window should contain information about the size of the file To inspect the contents of the file go to the middle pane and use the middle mouse button to do a get contents Now you should see the contents of junkfile reappear in the bottom pane of the File List window Manipulating Windows Themselves 33 The right mouse button menu normally has commands that apply to windows themselves in contrast to the contents of windows Choose a window on the display and activate it by clicking with the left mouse button Now press and hold the right mouse button You will see this menu under move frame collapse repaint title allows you to change the title of a window under allows you to bring a window into view if it is under another window Windows overlapping each other are arranged in an internal stack under pops the window at the arrow cursor point on the bottom of the stack to the top move allows you to change the position of a window on the display frame allows you to change the size of a window collapse allows you to delete from the screen all of a window except its title block repain
71. he 4 to a 6 and nothing else in the code choose the middle mouse button and press and hold it Find the command accept in the pop up menu It is below do it Select accept by highlighting it and releasing the middle mouse button You should observe that the Smalltalk busy signal the arrow cursor accompanied by the star appears for a fevv seconds and then returns to the ready for input plain arrow cursor You have just recompiled the example method and of course this had to be done to enter the altered code into the Smalltalk 80 system You are now ready to do it and observe the result of your change Do not forget to select Pen example first so that do it has something to operate on Do this now select Pen example and then do it You should see now that the lines of the figure are thicker than before If you like you can change the gray lines to black Select gray in the expression bic mask Form gray Change gray to black Select accept from the middle mouse button menu to recompile the method Next select Pen example and then do it You should observe that the figure changed from gray to black lines If you feel really adventurous you might try changing some of the other numerical constants that you see in the method code If the code does not accept properly an error message is inserted into the method and highlighted or you will see a window pop up that attempts to inform you about what the problem is If you do not understa
72. he class WireListController know what to do This is one way to do that down up Sensor redButtonPressed iffrue down Sensor cursorPoint up Sensor waitNoButton model replace model pinNear down with up 36 4404 Smalltalk 80 System User s Programming in the Smalltalk 80 System SecheduledControllers aControllerManager 7 A 5606 8 Figure 8 ScheduledControllers for Three Model View Controllers 4404 Smalltalk 80 System User s 37 Programming in the Smalitalk 80 System This code assumes that the user is looking at a window with the wire list endpoints marked and that the user wants to select a marked endpoint and move it to another location The message selector pinNear is a method that you have to write that decides what endpoint the user intended to select Viewports and Windows You may have realized as you went through this conceptual example that the screen coordinates of the Smalltalk 80 system and the coordinates of the wire list are probably not the same Look up the class WindowingTransformation in the System Browser In the definition of the class you find the instance variables window and viewport used The variable window is a Rectangle in the coordinate system of the model the wire list coordinates The variable viewport is a Rectangle in the destination coordinate system In this example the viewport coordinate system is the screen coordinate system 1024 by 1024 pi
73. ical relationship of objects Objects that are in subclasses understand all the methods known to objects in their superclasses This is a powerful feature of a hierarchical object oriented language like the Smalitalk 80 language The Syntax of the Smalltalk 80 Language A good vvay to get the flavor of the Smalltalk 80 language is to take a look at some code from the system In Section 3 you are asked to find this code run it and make some changes to it See Section 3 for a tutorial introduction to the System Browser where you will find this code An Example of Smalltalk Code This example method called example for the class Pen draws a square spiral figure on the screen in gray moderately thick lines Refer to the tutorial to execute this code 4404 Smalltalk 80 System User s 7 A Smalltalk 80 System Overview Each line of this example is commented on below example Draws a spiral in gray with a pen that is 4 pixels wide bic bic Pen new bic mask Form gray bic defaultNib 4 bic combinationRule Form under 1 to 50 do ii bic go i 4 bic turn 89 Pen example example This is the name or message selector of the method Draws a spiral in gray with a pen that Is 4 pixels wide This is a comment You will find that there is a comment line included immediately following the message selector in many of the methods found in the Smalltalk 80 system This initial comment usually giv
74. ifTrue ttrue tfalse isEmpty 4404 Smalltalk 80 System User s 47 4404 Smalltalk Reference Answer whether the receiver contains any elements tself size 0 occurrencesOf anObject Answer how many of the receiver s elements are equal to anObject tally tally self do each anObject each ifTrue tally lt tally 11 ttally Title Changes The title menu option is an addition to the right button menu When it is selected you are asked for the name of the new title for the window The title tab is then repainted with the new name under move frame collapse repaint Window Management Windows do not unnecessarily repaint themselves When a window is moved or closed the parts of the visible windows immediately underneath it are repainted The repaint menu item in the right button menu causes a window to be repainted to clean up from unscheduled graphics By default each time a window is de emphasized the visibie contents of the window arc saved in a form This form allows the window to be displayed quickly the next time it becomes active The System Transcript window is an exception to this convention since it can be modified while inactive Since each window has a corresponding form the existence of many windows can use a considerable amount of memory An option is provided to turn off the default storage of these forms To exercise this option execute the expression Smalltalk
75. int to note is that each individual controller only gives up control when it wants to The controller manager cannot take control away from an individual view controller You can modify this if you want for your own applications though After an individual controller gives up control the controller manager continues to poll all of the currently scheduled controllers until it finds that another one wants control A Conceptual Example Suppose you wanted to interactively allow a user to change the routing of wires on a prototype wire wrapped circuit board The model would be an ordered array of numbers in some coordinate system related to the dimensions of the circuit board Coordinate pairs would represent the positions of endpoints of wires And the ordered array would then represent a wire list See Figure 9 To realize this in the Smalltalk 80 system you would have to create an appropriate view and controller for the wire list model data You might come up with something like the following Smalltalk pseudocode You would have to define the method display for the class WireListView so that it would know how to display itself This is one way to do that wire wire LinearFit new model do each wire add each wire display The class LinearFit is a subclass of DisplayObject and Path so it has quite a bit of intelligence that you can make use of You would also need to define a method selector controlActivity to let t
76. ist Example 5606 9 VIEWPORT WINDOW 5606 10 Figure 10 Window Viewport Relationship 4404 Smalltalk 80 System User s 39 Programming in the Smalitalk 80 System SubVievv displayBox topVievv vievvport a topView window 2 subView viewport subView window 5606 11 Figure 11 Composition of Multiple Window Viewport Transformation 40 4404 Smalltalk 80 System User s SECTION 5 4404 SMALLTALK REFERENCE The information in this section primarily documents additions and enhancements that have been made to the Smalltalk 80 System Version 2 in order to create the 4404 version of the Smalltalk 80 system Most of the additions and enhancements involve the interface between the 4404 operating system and the Smalltalk 80 system The current release of the 4404 Smalltalk 80 system is Version T2 1 The Smalitalk 80 System in the 4404 OS Environment Making System Calls Sometimes you may want to make 4404 operating system calls from the Smalltalk 80 system There are a number of methods supporting system calls in the 4404 Smalltalk 80 system These methods are defined in the class TekSystemCall You can use the System Browser to find these methods Choose category Files Support class TekSystemCall and message categories display instance creation OT system dependent operations to see the system call methods The message category display instance creation deals with display operations The me
77. itten to the new file If the file testResults does not exist and a read operation is attempted an error is produced If the file testResults does not exist and a write operation is attempted the file is created opened for reading and writing One can query the existence of such a file before doing input or output For example 1 Disk file TestResulis f exists answers true if the yet to be opened file already exists 4404 Smalltalk 80 System User s 49 4404 Smalltalk Reference Sending the message readWrite to a FileStream created with the file message insures that no backup is made This allows updates in place For special devices like the sound device dev sound which can only be opened for writing use the oldWriteOnlyFile message f Disk oldWriteOnlyFile dev sound f binary f nextPut soundDevByteArrayBuffer f close The oldWriteOnlyFile message says that this file is intended to be a previously existing file hence do not employ the back up mechanism which is to be opened strictly in a writeOnly mode The file system is sophisticated enough to manage the opening and closing of files fairly transparently An attempt to read a closed file causes the file to be opened If an attempt is made to open a file that is referenced by another open FileStream an attempt is made to close the already open file Its position is retained so that later data transfers can resume unaffected by the closure It is
78. llection CsortBlock Set taliy Dictionary IdentityDictionary valueArray MethodDictionary 0 LiteralDictionary SystemDictionary 0 IdentitySet 0 Compiler sourceStream requestor class context Controller model view sensor BinaryChoiceController FormMenuController MouseMenuController redButtonMenu redButtonMessages yellowButtonMenw yellowButtonMessages blueButtonMenu TplueButtonMessages BitEditor scale squareForm color FormEditor form tool grid togglegrid mode previousToolf color unNormalizedColor xgridOn ygridOn ToolMenu underToolMenu ScrollController scrollBar marker savedArea ListController LockedListController ChangeListController SelectioninListConiroller ParagraphEditor paragraph startBlock stopBlock beginTypelnBlock emphasisHere initialText selectionShowing currentFont echoLocation echoForm SiringHolderConiroller isLockingOn ChangeController FillinTheBlankController CRFilllnTheBlankController ProjectController TextCollectorController 4404 Smalltalk 80 System User s 55 Smalitalk Classes List TextController CodeController AlvvaysAcceptCodeController OnlyWhenSelectedCodeController StandardSystemController sta
79. mUtility aCommand withArgs anOrderedCollection pipe task inputSide resultOfProgram pipe Pipe new task Subtask fork aCommand vithArgs an rderedCollection then pipe mapvriteTo 1 pipe mapWriteTo 2 pipe closeVrite closeReadl task start isNil ifTrue pipe closeWrite closeRead self error Cannot execute aCommand pipe closeWrite Cursor execute showWhile inputSide PipeReadStream openOn pipe resultOfProgram inputSide contentsOfEntireFile task waitOn inputSide close task abnormalTermination ifTrue self error Error from system utility resultOfProgram copyUpTo Character cr task release tresultOfProgram This method contains code to Pass arguments to the program in the form of an OrderedCollection e Check for failure of the child task task start isNil Test for abnormal termination of the child task Failure of the child task necessitates the closing of any pipes created for use in the subtask The parent task which creates these Pipes is responsible for closing them Neglecting to close these pipes might mean the Smalltalk parent task could run out of file descriptors Examples Using execSystemUtility withArgs Here are some examples that demonstrate how to use execSystemUtility withArgs To execute a program with arguments Application Note 4 5 Subtask Support fileName timingData flags tsa TekSystemCall execSystemUtility bin dir wit
80. many kinds of specialized views such as the classes FormView ListView StandardSystemView and BrowserView These views are suited to displaying the special kinds of models their names suggest A controller is the mechanism that you use to interact with a model displayed in a window A controller also interacts with a controller manager so that activity in multiple windows or multiple views within one window is appropriately coordinated A controller pays attention to cursor position and mouse button activity The Model View Controller Triad Controllers and views are linked internally by instance variables that refer to each other and to the model But the model does not refer directly back to its own controller and view The idea is to keep models simple by not requiring them to know how to display themselves So in order to display information on the Smalltalk screen you need to deal with the mode view controller triad Roughly speaking each single paned window has one model view controller triad associated with it And by extension each multi paned window such as the System Browser has a model view controller triad for each pane Furthermore each subview for each pane is eventually related hierarchically to a top view that controls the entire set of subviews for the whole window See Figure 6 and Figure 7 View Displaying Protocol When a view is asked to display itself by some update action received by the controller as when you
81. mpNames Dictionarylnspector ok InstructionStream sender pe ContextPart stackp BlockContext nargs startpc home MethodContext method receiverMap receiver Decompiler constructor method instVars tempVars constTable stack statements TastPc exit TastJumpPc 56 4404 Smalltalk 80 System User s Smalltalk Classes List tastReturnPc limit hasValue InstructionPrinter stream oldPC KeyboardEvent keyCharacter metaState Link nextLink Process suspendedContext Priority myList Magnitude Character value Date day year LookupKey key Association value MessageTally class method tally receivers Number Float 0 Fraction numerator denominator Integer LargeNegativelnteger LargePositivelnteger Smalllnteger 0 Time hours minutes seconds Message selector args MethodDescription status whichCiass selecior ParseNode comment AssignmentNode variable value BlockNode argumenis statemenis returns nArgsNode size remoteCopyNode sourceRange endPC CascadeNode receiver messages DecompilerConsfructor method instVars nArgs TiteralValues tempVars Encoder scopeTable nTemps supered requestor class TiteralSiream s
82. n as much as possible You also use the System Browser window for adding new classes and methods and for modifying existing classes and methods See later in this section for a description of classes and methods 4404 Smalltalk 80 System User s 5 A Smalltalk 80 System Overview The System Transcript window collects text messages from the system or from programs that you write It allows you to monitor certain functions in the system For example when you recompile classes messages about this action automatically appear in the System Transcript The System Workspace window contains information about the many functions and Smalltalk 80 language templates appropriate to them Templates are examples of Smalltalk code that you edit and compile to get information you are seeking You find templates for how to open read and edit files how to do system crash recovery how to manage the system image file how to interrogate the system how to manage the changes you make to the system as you program etc Pop Up Menus A workspace window is a window that you can use to develop new Smalltalk code In this kind of window pressing the middle button of the mouse while the arrow cursor is within the borders of the window makes a pop up menu appear This menu has selections such as the following This puts a copy of currently selected text into a hidden buffer cut This deletes currently selected text from the s
83. ncedPriority shellTask start isNil ifTrue pipeln closeWrite closeRead pipeOut closeWrite closeRead self error Cannot execute a shell l pipeOut closeRead pipeln closeWrite shellIn PipeReadStream open n pipeln shellOut PipeVriteStream pipetut This method uses two pipes for two way communication It also assigns the highest possible priority to the subtask with the message enhancedPriority When the view is closed each instance of ShellTnterface cleans up with the release method Subtask Support release sysCall 1 Close pipes for interactive shell shellOut isValid ifFalse fselfl shellIn close shellOut close shellTask kill shellTask waitOn shellTask release TekSystemCal1 terminalOff value TekSystemCal1 cursorOn value Cursor cursorLink true Display enableCursorPanning Display enableJoydiskPanning Display setNormalVideo The shell subtask shellTask is terminated with the kill message The parent task waits for the shell subtask to terminate and then releases the instance of Subtask Other methods are invoked to reset states in case a subtask of the shell has modified the display Application Note 1 11 Subtask Support THE DETAILS OF STARTING A SUBTASK Here is the start method taken from the class Subtask This method contains low level details of how a subtask is actually exec ed start Start the receiver by executing a vfork code to set up the child t
84. nd either these a likelihood at this point choose the middle button menu selection abort or the right button menu selection close and try again to change the code Take a Short Break 26 At this point you might like to take a short break and go through the rest of the tutorial later If it is at all possible leave the system just as it is now Note that the display blanks out after about 10 minutes of no activity at the keyboard or mouse If this happens just move the mouse or press the shift key The display 4404 Smalitalk 80 System User s 19 The 4404 Smalltalk 80 System A Tutorial reappears just as you left it If you cannot do this go to the last step in this tutorial step 34 and quit the system then when you come back go to the beginning of the tutorial and repeat steps 1 through 6 then skip back to here Opening a Workspace Window 27 If you have not done so recently clean up the screen by placing the arrow cursor on the gray background and selecting restore display with the middle mouse button Now go back to the middle mouse button pop up menu and select workspace to open a workspace window A small square should appear along with an angle bracket at the upper left corner You can drag this square anywhere over the display you like even over already existing windows When you have the square where you want it depress and hold the left mouse button You will see that the angle bracket has shifted to the lo
85. not be directly filed into a Smalltalk 80 image but is intended to provide a more human readable format than that provided by the file out menu selection It can be regarded as a pretty printed version although no automatic formatting is performed on methods The pp files contain control characters for bold italic and normal fonts taken from from ANSI Standard X3 64 Note that changes that you file out from a Browser are removed from the System Change Set Refer to the Goldberg book for more about this Entries that you print out from a Browser are not removed From the operating system you can look at a file named Collection pp by typing list Collection pp There are no italic fonts for the terminal so italic entries are printed in the normal font To print the file on a Tektronix 4644 printer type samples printer print s Collection pp An example of this output might look like Object subclass Collection instanceVariableNames classVariableNames poolDictionaries category Collections Abstract Collection comment l am the abstract class of all collection classes Collection methodsFor accessing size Answer how many elements the receiver contains tally tally 0 self do each tally tally 11 ttally Collection methodsFor testing includes anObject Answer whether anObject is one of the receiver s elements self do each anObject each
86. ocode above representing the instance creation of the window must take care of arranging the subviews properly in the top view The first three blocks of pseudocode construct the window and the final line of code tells the topView s controller to schedule this window for display and make it the active window C topVievv M C SubView Cy gt SubView R VZ 5606 7 Figure 7 Hierarchy of Model View Controllers Controllers and Controller Protocol If you look at the class Controller you see that like the class View it has quite a few subclasses which are specialized controllers Some of these are MouseMenuController ScrollController ListController StandardSystemController and so forth You may decide that none of these controllers fits your application and create your own perhaps as a modification of MouseMenuController Each controller receives this basic sequence of messages controllnitialize controlLoop isControlActive controlActivity controlTerminate 4404 Smalltalk 80 System User s 35 Programming in the Smalltalk 80 System The overall controller manager of the system the global variable ScheduledControllers constantly monitors the position and activity of the mouse See Figure 8 When mouse button activity occurs within a window the controller manager usually passes control to that window s controller and the window s controller then executes the sequence shown above An important po
87. on pop up menu Highlight the expression Pen example in the workspace Select the middie mouse button command cut It does what you would expect it removes the text that you highlighted It also does what you might expect it puts the text in a temporary buffer in memory Now choose the middle mouse button command undo You should see the expression reappear Try this Highlight Pen example as before But now select copy from the middle mouse button menu You have just copied the text Pen example into the buffer in memory Now move the arrow cursor into the gray background and press and hold 4404 Smalltalk 80 System User s The 4404 Smalltalk 80 System A Tutorial the middle mouse button Choose the workspace command and open a workspace window With the arrow cursor in the workspace window choose paste from the middle mouse button menu You should see the text Pen example appear in the window You may of course copy and paste virtually any size block of text you like copy and paste allow you to very easily shift blocks of text between windows If you would like to get rid of the workspace window after you are done with it choose the right mouse button command close Communicating with the 4404 File System 30 After you have worked with the Smalltalk 80 system for a short while you will undoubtedly want to communicate with the 4404 operating system to get a directory of files look at the contents of files output text or code in a
88. ontext This primitive and primitive 130 are the only acceptable ways to explicitly modify a context s stack pointer Primitive 134 primSysCall This is a primitive method in class TekSystemCall It causes the operating system call specified by the receiving object to be executed If the system call is executed without error true is returned If an error occurs during the system call then false is returned Primitive 135 primDispCall This is a primitive in class TekSystemCall It specifies a display related system call to the operating system If the call is executed without error true is returned If an error occurs during the call then false is returned Primitive 136 primShell This is a primitive method in class ScreenController It forks a shell from the operating system with a duplicate of the parent shell s history When the shell exits control is returned to the Smalltalk 80 system true is returned unless the system call fails in which case false is returned 4404 Smalltalk 80 Virtual Image Enhancements A number of image enhancements have been made to the Smalltalk 80 Version 2 virtual image File Lists and Directory Browsers The Files and File List Browsers are described in the Goldberg book in Chapter 22 The File System has been extended to support the creation and browsing of directories The wildcard characters and can only be used in the file name itself and not in the path name The asterisk
89. ow cursor around the System Transcript window Note that parts of text are highlighted and unhighlighted as you move Release the button move the arrow cursor to a new initial location press and hold down the left mouse button again and move the arrow cursor around Do this a few times till you get a feeling for how highlighting works Note that the arrow cursor remembers an initial position Now go to the line just above or below all of the text or to the very beginning of all text in the window if there is no blank line at the beginning Press and release twice or three times Note that the entire text is now highlighted The text or code that is highlighted is selected and ready to be manipulated usually by applying a command to it 4404 Smalltalk 80 System User s 16 4404 Smalltalk 80 System A Tutorial Deselect unhighlight all of the text in the System Transcript window Pick out a word in the text move the arrow cursor point just before the word press and hold the left button move the arrow cursor to the right along the line and at the end of the word release the button You should see your selected word highlighted Now type another word You should see your word replacing the previously highlighted word This is one way to replace text or code in a window In fact typing always inserts new text and replaces the current text selection This is even true of the caret text position cursor if you think of i
90. ple ScreenController 055 11 method fork vithArgs then is passeda block which modifies some of these reactions Code in this block is executed by the child task only The reaction to several interrupts is modified with the method setInterrupt to in both the parent and child task Here is a simplified and stripped down copy of the method ScreenController forkOSShell Application Note 1 7 Subtask Support forkOSshell Simplified for example location task oldSIGHUPValue oldSIGINTValue oldSIGQUITValue sysCall oldSIGTERMValue oldSIGHUPValue TekSystemCall setInterrupt 1 to 1 oldSIGINTValue TekSystemCall setInterrupt 2 to 1 oldSIGQUITValue TekSystemCall setInterrupt 3 to 1 oldSIGTERMValue TekSystemCall setlnterrupt 11 to 1 task Subtask fork bin shell withArgs OrderedCollection with s1 then TekSystemCall setInterrupt 1 to 0 TekSystemCal1 setlnterrupt 2 to 0 TekSystemCal1 setInterrupt 3 to TekSystemCal1 setInterrupt 11 to sysCall TekSystemCall terminalOn sysCall value error task start error isNil ifFalse task absoluteWait task release TekSystemCall setInterrupt 1 to oldSIGHUPValue TekSystemCall setInterrupt 2 to oldSIGINTValue TekSystemCall setInterrupt 3 to oldSIGQUITValue TekSystemCall setInterrupt 11 to oldSIGTERMValue sysCall TekSystemCall terminalOff sysCall value ScheduledControllers restore error isNil ifTrue 9517
91. pm Select some other files and look at the information in the bottom pane Some of the files are directories Choose the file name system this should be a directory Choose the middle mouse button menu command list contents Observe that the bottom pane now contains a list of the files in that directory If you would like to look at more than the names of the files go to the middle mouse button menu and choose the command spawn You will note that a second File List window opens When you are through looking at these files choose the right mouse button menu command close and go back to the original File List window 4404 Smalltalk 80 System User s 21 The 4404 Smalltalk 80 System A Tutorial l Copyright c 1983 Xerox C Snapshot at 19 Nq All rights reserved 1 38 09 pm The Smalltalk 80tm System Version T2 1 Copyright 1989 Xerox Corp AH rights reserved Enhancements version T2 1 again copyright 1984 Tektronix inc undo All rights reserved copy N ic M A 7 0 Create File System Make the smalitelk home directory d the smailtalk home directory was invoked Disk FileDirectory currentDirectory Set painter to smaiitatk source and changes files poolDictionaries category Collectlons Streams 5606 5 Figure 5 File List Window Writing Files Out to the 4404 Operating System 22 22 Suppose now that you would like to create a new file and put some text from the Smallt
92. ps system call See the 4404 Reference Manual for more details Once a pipe s file descriptor is mapped it becomes obsolete and should be closed For example the child task may want to write to the pipe but the program is designed so write operations go to standard output The write file descriptor of the pipe must be mapped to standard output s file descriptor 1 and the write file descriptor should be closed The effect of the mapping in this example is for write operations on standard output from the child task to be performed on the write end of the pipe instead CLASS DESCRIPTIONS Instances of the class Subtask represent operating system child tasks The process of creating an instance of this class includes specifying an executable program and optionally arguments to the program and environmental variables A block representing code to be executed by the child task can also be specified Subtask contains protocol for invoking terminating and waiting for a child task The invocation of a child task may include modification of the child s priorities and environment variabies The metaciass contains protocoi for managing these chiid tasks The ciass Pipe represents an operating system pipe Instance creation causes a pipe to be created with two open file descriptors one for each end of the pipe Protocol exists for mapping ends of the pipe to arbitrary file descriptors The class PipeStream a subclass of ExternalStream is an abst
93. r howmany count Makes an entry in system s locked record table ofstat fileDescriptor buffer buff Gets the status of an open file open fileName mode modeBits Opens a file read fileDescriptor buffer buff nbytes numberOfBytes Performs a read operation into the buffer seek fileDescriptor offset position whence start Positions a file s read write pointer relative to start setpr priority 4404 Smalltalk 80 System User s 43 4404 Smalltalk Reference Sets the priority setuld userlD Sets the actual user ID and the effective user ID to userID spint taskNumber an interrupt Sends a program an interrupt status fileName buffer buf Reads the status information of a file into the buffer buf term terminatingStatus Terminates a task with the status terminatingStatus where a zero status means no error occurred time tbuff Returns the system s current time in the buffer tbuff truncate fileDescriptor Truncates a file at the current position ttime tbuff Returns accounting time information about a task in the buffer tbuff ttyget fileDescriptor buffer ttybuff Ttybuff should be a WordArray of size 3 ttynumber Gets the number of the calling task s terminal ttyset fileDescriptor buffer ttybuff Sets the tty information as described in ttyget unlink fileName Unlinks a file update Update the information on the disks urec fileDescriptor Unlocks a file record wait Waits for a
94. r selecting text in a window moving the text position cursor in a window or selecting an entire window to be the active window The middle button s the yellow button in the Addison Wesley Smalltalk books primary use is to pop up a menu appropriate to the location of the mouse it is context sensitive You select from the menu and the command is performed The middle button menu commands apply to the contents of a currently selected window For example you can do things like cut paste and copy blocks of text in some windows The right button the blue button in the Addison Wesley Smalltalk books generally pops up a menu with commands that apply to the window itself and not to the contents of the window You can do things like moving framing and closing windows Special Purpose Windows There are a number of special purpose windows to make your life easier in the Smalltalk 80 system Among these are the System Browser the System Transcript and the System Workspace There are other system created windows but these are the main ones The System Browser window is your key to finding information in the system Since the Smalltalk 80 virtual image consists of over 200 classes you need to be able to find out about them quickly and easily The System Browser window shows you not only the system classes but also all the messages that can be sent to them Classes and messages are both categorized to narrow your search for informatio
95. ract class Since instances of ExternalStream are positionable and pipes are not positionable one of PipeStream s purposes is to provide protocol for filtering out inappropriate inherited methods It also contains a method for closing a PipeStream or one of its subclasses which also closes its associated pipe file descriptor Protocol also exists for mode changes to binary or text PipeStream has two subclasses PipeReadStream and PipeWriteStream Each of these subclasses is created by opening on an instance of Pipe Each has protocol appropriate for its function PipeReadStream has protocol for streaming over data read from a pipe PipeReadStream buffers its data from the pipe However PipeWriteStream does not buffer its data Both of these classes support non homogeneous accesses that is reading or writing different sized pieces of data These classes inherit higher Subtask Support level protocol involving Padding e Accessing strings numbers and words fileln and fileOut SUBTASK EXAMPLES Here is an example vvhich uses Subtask Assume the existence of an executable file bin simpleUtility a program with no input output or arguments executeSimple Execute a pretend progran task task Subtask fork bin simpleUtility then task start task vait n task release The method fork then creates an instance of Subtask This object assigned to the variable task contains all the information needed to crea
96. rsion 2 User Interface Differences Although the 4404 version of the Smalltalk 80 system and the Goldberg book version of the Smalltalk 80 system are very similar there are some differences A list of these differences follows On page 6 Chapter 1 The 4404 virtual screen coordinates are 1023 1023 at the lower right corner The visible part of the screen is 640 pixels wide by 480 pixels high The joydisk on the keyboard does a hardware scroll through the entire range of virtual screen 50 4404 Smalltalk 80 System User s 4404 Smalltatk Reference coordinates On page 7 Chapter 1 The 4404 keyboard has a rubout key labeled Rub Out instead of a delete key The backspace key is labeled Back Space and the line feed key is labeled Line Feed There is also a Caps Lock key The 4404 keyboard also has special keys for the assignment arrow and the return arrow The assignment arrow is the unshifted leftmost key in the upper row of keys The return arrow is the shifted version of the same key Also the programmable key F12 puts the arrow cursor in the center of the screen On page 14 Section 1 2 Getting Started See the accompanying Invoking the Interpreter heading and Section 4 for how to get started On page 14 System Files The 4404 Smalltalk 80 system directory is described under the Smalltalk File Structure heading in this section On page 24 26 Saving Information When a snapshot is made a prompter asks you for the name
97. rule is press hold decide release Later in the tutorial you will encounter the phrase to click a mouse button This means to press and immediately release a button Clicking is used less often than pressing holding deciding and releasing in the Smalltalk 80 system How to Select Smalltalk Objects 13 14 15 14 Move the arrow cursor to the inside of the System Transcript window Remember that the tip of the arrovv is the active selection point of the arrovv cursor Press and immediately release the left mouse button Note that the window s title box turns to black showing you that the window is selected and active Left button activity anywhere in a window including its title box activates that window Move the arrow cursor to the System Transcript window and activate it press and release the left mouse button Note that in addition to some English text there is a small dark caret cursor This is the point at which typed characters appear in the text Type a few characters Take up the mouse again and move the arrow cursor between two characters along a line of text Press and release the left mouse button Note that the caret cursor has moved to that point Type a few more characters If you like move the caret to the end of the last line of text type a few Carriage returns and type a sentence or two and watch the text automatically wrap around Press and hold down the left mouse button while you move the arr
98. s and it documents the implementation and programming aspects of the Smalltalk 80 system on the 4404 If you have little or no experience with the Smalltalk 80 system then you should probably read through the entire manual Section 2 gives a brief summary of the main features of the Smalltalk 80 system for those who are not acquainted with it and Section 3 is a Smalltalk tutorial on the 4404 If you are an experienced Smalltalk programmer you can turn immediately to Section 4 Programming in the Smalltalk 80 System In Section 4 you are given just what you need to get quickly into the Smalltalk 80 system on the 4404 Regardless of whether you are a novice or an expert in Smalltalk programming you need to how to operate the 4404 first You should also know something about the 4404 operating system with which the Smalltalk 80 system communicates You can achieve this understanding by reading through the 4404 Artificial Intelligence System User s Manual The presentation of information in this manual assumes that you have read through the 4404 AIS User s Manual About This Manual Here is a summary of what you will find in this manual 6 Section 1 This tells you what is in this manual and where to find it It tells you about the Addison Wesley books on the Smalltalk 80 system and describes the 4404 documentation 4404 Smalltalk 80 System User s 1 Introduction Section 2 This is a brief introduction for those who are not acquainte
99. saveSpace true In conjunction with the saving of forms for windows is the redisplay of parts of inactive windows which have been obscured For instance if one window were covering a second window and the first window is closed then the part of the second window which was previously covered by the first window would be redisplayed The saved form for the first window is used to redisplay the obscured portion In the case of redisplay of the System Transcript window the obscured portions are colored white The existence of many obscured windows needing to be redisplayed can be time consuming An option is provided to turn off the default redisplay of obscured windows To exercise this option execute the expression Smalltalk frills false 48 4404 Smalltalk 80 System User s 4404 Smalltalk Reference Several combinations of these two options exist One may wish to save the window forms in order to display windows quickly but not want to redisplay obscured windows In this case set both saveSpace and frills to false Another reasonable combination is to redisplay obscured windows but not save forms Since the forms associated with windows are not saved obscured parts of windows are filled in with a white form This combination may be used by people who want to limit memory usage and yet want to know explicitly where all the windows are In this case both saveSpace and frills would be true Cursor Center Key The cursor center key F12
100. sible to reposition a pipe Usually the parent task creates a pipe Each end of the pipe is assigned a file descriptor one for reading and one for writing When a subtask is created it inherits these open file descriptors The parent task remembers one file descriptor the one which is appropriate for its direction of communication For example if the parent task wants to send information to the child the parent remembers the file descriptor for writing Since the parent will not be using the reading end of the Application Note 424 Subtask Support pipe it should close this unused end The child task must also remember the appropriate file descriptor and close the file descriptor corresponding to the unused end of the pipe Neglecting to close these unused pipe file descriptors might mean the task could run out of file descriptors since there is a limit of 32 open file descriptors per task Sometimes it is not possible for the child task to know that it should use the pipe s file descriptors for reading and vvriting For instance the child task might vvant to exec a program that vvrites on standard output Even if the program vvere avvare of the use of pipes it may not be possible for the program to modify itself to use the pipe s file descriptor for writing In this case it is possible for the child task to redirect its I O by mapping its pipe descriptors to known file descriptors This mapping is accomplished through the use of the du
101. sk activity as the Smalltalk 80 system files are loaded into main memory These files are very large so be prepared to wait approximately forty seconds as they load You will see the Smalltalk interpreter sign on message appear fairly soon after which the interpreter loads in the Smalltalk 80 image file While you are waiting for the Smalltalk 80 system to load make sure that the Mouse Pad is secured on a flat level surface to the right or left of the Display CPU unit Set the mouse on the pad with the cord leading away from you This orients the three mouse buttons away from you This is the correct orientation for the mouse Learning Mouse Mechanics 7 You should now see the initial Smalltalk display on the screen See Figure 1 You will note that there are a number of boxes with text and Smalltalk code in them The boxes and parts of boxes are window borders and panes within the window borders Grasp the mouse and while keeping it flat against the mouse pad move it back and forth and up and down around the pad Observe that the black arrow cursor moves in concert with your motions on the pad The tip of the arrow is the pointing part of the arrow cursor Note that as you moved the mouse over one of the windows one of the small title boxes at the upper left corner of one of the three visible windows became highlighted that is turned to white letters on a black background You have just If a password has been installed on your s
102. ssage category system dependent operations deals with a low level interface to the operating system Refer to the 4404 AIS Reference Manual for a complete description of system calls The message selectors found in the display instance creation category all have higher level methods that you can access to achieve the same functionality so you will probably not use these system calls Go to the System Browser and select these category Graphics Display Objects DisplayScreen and message category display functions For example choose setinverseVideo You can see that the method uses the TekSystemCall method whiteOnBlack in a simple and straightforward manner This is true of all of the display instance creation TekSystemCall methods Two System Call Examples To see how to use the system call methods look at two examples from the system itself Use the System Browser to find the senders of open mode and link to Click on the following selections category Files Support class TekSystemCall message category system dependent operations method link to Find all the senders of linkto by choosing the 4404 Smalltalk 80 System User s 41 4404 Smalltalk Reference middle button senders command You will see a senders of link to window open Choose TekSystemCall class rename as Note that the method rename as uses the system call method link to in the second line of code self is understood as TekSystemCall in this line The link to method
103. standard image the Disk is set to bin Be careful You may not have permission to write to bin and most of the system directories Attempts to write to a protected Girectory are denied Dependents ControlManager allUnscheduledDependentViews do aView aView release Ask the ControlManager to release all views which are unscheduled but still in Object s dependency dictionary These unscheduled views may result from user interrupts or incorrectly written code Globals Smalltalk frills false for slow machines 4404 Smalltalk 80 System User s 29 Programming in the Smalltalk 80 System The normal behavior with frills set to true is to restore previously occluded windows Do not repaint occluded windows just leave these areas gray if frills is false Smalltalk saveSpace true for limited memory machines Forms for each window are normally saved so that the windows can be quickly restored To conserve memory set the saveSpace flag to true so that these forms are not saved In that case a window is repainted the slow way each time it becomes active Display DisplayScreen displayExtent 1024 1024 The normal size for the 4404 virtual screen is 1024 by 1024 pixels DisplayScreen displayExtent 640 480 640 by 480 pixels is the size of the visible screen If this expression is executed the only portion of the screen that is updated is the upper left viewport Display getViewportLocation Examine the origin
104. still a good idea to close files explicitly Closing forces all buffers to be flushed to the physical file thus protecting from unexpected data loss in the event of a crash Framing Rectangular Regions The standard frame specification method reverses the rectangular region Workspace Variables If a previously undefined variable is assigned a value within a workspace through an assignment statement the variable is automatically declared as a local variable Its scope is defined for the entire duration of the workspace or until it is assigned the value nil The Smalltalk compiler defines and later references variables in the context of invoking workspaces The spelling corrector is not invoked when an undefined name appears on the ieit of an assignment The Smalltalk debugger without reference to the original workspace is able to correctly recompile a method s source code Since each workspace has its own dictionary of local variables objects that are referenced by a workspace variable exist for the lifetime of the workspace If you are concerned with memory space usage assign nil to all the variables within a workspace or copy the text from one workspace into a new one and delete the old workspace Within each workspace you can examine the current contents of the workspace variable dictionary by evaluating the expression WorkspaceVariables inspect or by asking the object named WorkspaceVariables to print itself 4404 and Smalltalk Ve
105. t allows you to redisplay the contents of the current window close allows you to remove a window entirely from the display and discard all of the contents of the window too Take the time now to work with these commands until you feel reasonably comfortable with their operation 4404 Smalltalk 80 System User s 23 The 4404 Smalltalk 80 System A Tutorial Saving Your Work and Quiting 34 After you are through with this tutorial session you will probably want to quit without saving your work To do this use the middle mouse button menu command quit If you are ready to quit do this now You will see a second window pop up As you can see you have three choices For now choose Quit without saving However in later sessions you will undoubtedly want to save your work Then you should choose Save then quit You will see a prompter window pop up with a default file name You can choose the default name by accepting it or entering a carriage return Or you can enter your own file name If you like save the image file as publicimylmage or enter your own image file name At this time the system makes what is called a snapshot of your current image When you wish to take up exactly where you left off with your work just invoke your own snapshot image file by typing smalltalk mylmage at the operating system prompt You have now finished this tutorial Congratulations You should now be able to reinforce w
106. t as a zero length selection There is nothing to replace in this case but it does insert whatever you type How to Scroll Text in a Window 17 Now move to the System Workspace window and press and release the left mouse button See Figure 2 This selects the System Workspace window to be the active window Move the arrow cursor into the small box attached to the side of the main window box This is the scroll bar region In windows that have a lot of text you use this feature to move the text up or down in the window There are three basic ways to use the scroll bar you can move text up one or more lines at a time move it down one or more lines at a time or move yourself quickly to some part of the whole text The gray scroll bar s length compared to the whole scroll box shows you approximately what proportion of the entire text is currently in the window The gray scroll bar also shows you by where it is in the scroll box whether you are at the top middle or bottom of the entire text For example if you see the gray scroll bar relatively small at the top of the scroll box then you know that you are looking at the very beginning of a lot of text Note that as you move the arrow cursor horizontally across the scroll box three new cursors appear a downward pointing half arrow a horizontally pointing arrow and an upward pointing half arrow Find the downward pointing half arrow and press and release the left mouse button Observe t
107. te an OS subtask to execute the program bin simpleUtility However an actual subtask is not created by this method The method start issues the system calls vfork and exec to create and run the subtask The method vait n instructs the currently executing Smalltalk process to wait for the subtask to terminate Release discards the Subtask object Here is a somewhat more complicated example execSystemUtility aCommand pipe task inputSide resultOfProgram pipee Pipe new task Subtask fork aCommand then pipe mapWriteTo 1 pipe mapWriteTo 2 pipe closeWrite closeReadl task start pipe closeWrite inputSide PipeReadStream openOn pipe resultOfProgram inputSide contentsOfEntireFile task waitOn inputSide close task release tresultOfProgram In this method execSystemUtility a pipe is created to establish one way communication with the subtask Two pipes are required for two way communication The code in the block is executed by the subtask after the vfork Application Note 1 3 Subtask Support system call and before the exec system call All the rest of the code in execSystemUtility is executed by the parent task Pipe connections in the child task are established in the block In this case the child task s standard output file descriptor 1 and standard error file descriptor 2 are redirected to the pipe through the use of the mapWriteTo method When the child task writes to standard output or stand
108. te its methods The Smalltalk 80 system consists of a large number over 200 predefined classes of objects These classes are arranged in a hierarchical order to facilitate the inheritance of the many methods that apply to them For example the classes Fraction and Float are subclasses of the class Number Fraction and Float since they are subclasses inherit and thus understand all the methods that Number does In addition Fraction and Float understand methods that are unique to them that Number does not understand Methods and Messages Methods are essentially implementations of algorithms The execution of methods is how objects communicate with each other This is how everything gets done in the system You can think of methods as roughly equivalent to functions in the C language When you execute Smalltalk code you send messages to objects by using the names of methods called message selectors If the object recognizes a specific message selector it carries out the actions described by the method associated with that message selector Many message selectors must be accompanied by arguments You can think of this as similar to the passing of parameters in subroutines However the arguments of message selectors are objects and because of the internal structure of objects the analogy with parameter passing is incomplete But this analogy does adequately express the basic idea Methods are shared among objects because of the hierarch
109. ted in the elimination of the classes File and FilePage On page 354 Chapter 16 Spelling correction If a previously undefined variable appears to the left of an assignment operator within a workspace the variable is automatically declared to be a local variable when the expression is evaluated Its scope remains for the lifetime of the workspace or until it is assigned the value nil On page 435 Chapter 22 Print out sends the pretty printed code to a file On page 440 File List Browser Support for directories is added to FileLists see the File Lists and Directory Browsers section of this document On page 460 461 Saving Your System State The default snapshot name is not the same as the first part of the name found as the first element of the global array SourceFiles The extension im is not appended to 4404 image names A new changes file is not made 4404 Smalltalk 80 System User s 51 4404 Smalltalk Reference for each image the name of the changes file remains unchanged On page 467 The System Audit Trail When a snapshot has completed correctly the changes file is marked with the date time and image file name in addition to the SN APSHOT notation Smalltalk File Structure The smalitalk Directory The smalltalk directory contains the standardImage file and the system demo and fileln directories The standardImage file is the default virtual image containing Tektronix enhancements The interpr
110. tus NotifierController NoController 0 SwitchController selector arguments cursor ndicatorOnSvvitchController LockedSwitchController ControlManager scheduledControllers activeController activeControllerProcess screenController Delay delayDuration resumptionTime delaySemaphore delaylnProgress DisplayObiect DisplayMedium 0 Form bits width height offset Cursor DisplayScreen DisplayText textStyl offset form Paragraph clippingRectangle compositionRectangle destinationForm mask marginTabsLevel Tirstindent restindent rightlndent lines TastLin outputMedium TextList 1ist nfiniteForm pattemForm OpaqueForm figur shape Path form collectionOfPoints Arc quadrant radius center Circle Curve Line LinearFit 0 Spline derivatives Explainer class selector instance context methodText FileModel fileName FileList ist myPattern isReading TileMenu FormButtonCache offset form value TnitialState InputSensor keyboardMap InputState x y bitState T1shiftState rshiftState ctr State TockState metaState keyboardQueue deltaTime baseTime imeProtect Inspector obiect field Contextinspector te
111. uotation marks since this would make 4404 Smalltalk 80 System User s 17 The 4404 Smalltalk 80 System A Tutorial 23 18 Vyafrkspae Make the smalltalk home directory float 3 47 O sin 0 0 1 cos 0 540302 Figure 4 Workspace Window the expression into a comment There are two ways to do this 1 put the arrow cursor point between the initial double quotation mark and the P press and hold the ieft mouse button run the cursor to the right tili you reach the ast 6 and release the button 2 put the arrow cursor between the double quotation mark and the P and click the left mouse button twice without moving the mouse For the second method to work you must place the arrow cursor point immediately after the double quotation mark if there are any spaces between the double quotation mark and the first character on the line With just Pen example highlighted press and hold the middle mouse button Observe that a pop up menu appears overlaying the window information Continue to hold down the middle mouse button while you move the arrow cursor up and down the menu You see a number of commands that you can invoke Here again you invoke whatever command is highlighted when you release the middle mouse button To run the Pen example method choose the command do it You should see a square spiral shape appear on the display Also note that as the method is executed the arrow cursor changes to an arrow cursor with a st
112. upper left corner of the current viewport that part of the virtual screen that is visible Display setinverseVideo Display white characters on a black background Display setNormalVideo Display black characters on a white background Measurements MessageTally spyOn Behavior compileAll Open an edit window on the performance analysis of the block expression MessageTally spyOn Behavior compileAll to spy resulis FileStream oldFileNamed spy resulis edit Write the spy results to a file and open an edit window on its contents Miscellaneous Programming Tips Debugging Smalltalk Code When you are modifying methods or developing new ones you might insert the following expressions into appropriate places in your code self halt self halt LabelSiring for the Notifier Transcript show counter counter printString cr Delay forSeconds 3 wait Cursor wait showWhile Sensor waitButton Sensor leftShiftDown ifTrue put some expressions here 30 4404 Smalltalk 80 System User s Programming in the Smalltalk 80 System You may create breakpoints by sending a message to an object to halt Sometimes you may wish to print out debugging information to the System Transcript If you re debugging something like displaying text in a window halting or sending text to the System Transcript would cause an infinite loop In these cases you might wish to pause at appropriate places in the execution by delayin
113. wer right corner Now stretch the square out by moving diagonally away from the upper left corner When the window fills about a third or so of the display release the left mouse button You will note that the depression of the left mouse button anchors the upper left corner and the release fixes the size of the window See Figure 4 Evaluating Smalltalk Expressions in a Workspace 28 Workspace windows are where you usually develop Smalltalk code Place the arrow cursor within the workspace window and click the left mouse button Set the arrow cursor to one side within the window Type these Smalltalk expressions in the workspace 3 4 0 sin 1 cos Pen example First highlight the expression 3 4 Now choose the middle mouse button menu command print it Note that 7 appears just to the right of the expression Any time you want to find out what a Smalltalk expression evaluates to you can choose print it Now select first O sin and print it and then 1 cos and print it The last expression Pen example is by now quite familiar to you Select it but this time select the do it command from the middle mouse button menu Observe that the Smalltalk 80 system understands the expression and executes it just as it did in the System Browser Manipulating Code or Text in a Workspace 29 20 To facilitate common text manipulation tasks the Smalltalk 80 system has implemented the commands undo copy cut and paste in the middle mouse butt
114. work with the Smalltalk 80 system You can become familiar with these components by reading through the 4404 AIS User s Manual Probably half an hour or so with this manual is sufficient The standard Smalltalk 80 system consists of four files as your 4404 is configured at the factory They are smalltalk This is the Smalltalk interpreter for the 4404 This file is found in the directory bin standardChanges This is the file that receives any changes you make to the standard system and it is found in the directory smalltalk system This file tends to grow each time you use the standardImage standardImage This is the default Smalltalk 80 virtual image file and it is found in the directory smalltalk standardSources This file contains the source code for each of the compiled methods in the standardImage file This file is found in the smalltalk system directory 4404 Smalltalk 80 System User s 25 Programming in the Smalltalk 80 System The Smalltalk interpreter is invoked by typing the smalltalk command This command has a single optional parameter that is the name of a Smalltalk 80 virtual image file If the parameter is omitted the interpreter loads the standard virtual image named smalltalk standardI mage After you have created your own virtual image file by using the save command you can load it instead of the standardImage If you are not in the same directory as your image you need to type the complete path
115. xels A view s window and viewport are used to form a WindowingTransformation See Figure 10 To make use of this transformation you would modify the previous example view to include model do each wire add self displayTransform Alternatively the sample controller can perform the inverse transformations with down view inverseDisplayTransform Sensor cursorPoint In a window with subviews two transformations would be required See Figure 11 The first transformation would carry coordinates from the subview window coordinate system to the subview viewport coordinate system The subview viewport coordinate system would actually be the same coordinate system as the top view s window coordinate system The second transformation would then carry coordinates from the top view s window coordinate system which is equal to the subview s viewport coordinate system to the top view s viewport coordinate system which is finally the 1024 by 1024 screen pixel coordinate system This brief overview of models views and controllers is meant to get you started For more information turn to the System Browser and examine the class View and its specialized view subclasses the class Controller and its specialized controller subclasses and the class WindowingTransformation 38 4404 Smalltalk 80 System User s Programming in the Smalltalk 80 System VVire List Diagram a n l Figure 9 User View of Wire L
116. ystem you must login to see this prompt See the 4404 AIS 12 User s Manual for more information 4404 Smalltalk 80 System User s The 4404 Smalltalk 80 System A Tutorial The Smalltalk 0t Copyright c 1989 Xe rights reserved Enhancements version Copyright 1984 Te rights reserved Snapshot at 19 November 1984 1 38 09 pm Create File System Atake the smalitaik h Disk FileDirectory dir lake the smalitalk ho smalltalk was invoked Disk FileDirectory cu System Browser Numeric Magnitudes Numeric Numbers Collections Abstract Collections Unordered Collections Sequencee Collections Text Collections Arrayed Collections Streams Coliactions Support Figure 1 Initial Screen of Standard Image selected that window to be the active window There is always only one active window 10 Now move the mouse so that the arrow cursor moves up against the right side of the display Watch the whole display move as you continue to move the mouse in the same direction While doing this you may reach the end of the mouse pad Just pick up the mouse and move it back to the other end of the pad and continue the movement in the same direction 11 Now move the mouse so that the arrow cursor moves down against the bottom of the display Watch the whole display move as you continue to move the mouse Again pick up the mouse and replace it on the pad as you need to to continue the movement

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