Tutorial on using FIELD
Contents
1. a w inside will mark any segments of code that warrant a warning from the compiler If no errors are found the dialog box will simply list the directory it entered and left Displaying compilation errors To display the error message for a line click the middle mouse button on the thumbs down or w annotation After you have finished reading the error message click on the accept button of the error dialog box Correcting Compilation Errors To correct the compilation errors you can use the any of the editor commands described in the Editing a file with FIELD section Removing an Error or Warning Annotation After you have corrected a compilation error or warning remove the annotation to the left of the line by clicking the middle mouse button on the annotation clicking on the box to the left of the word remove and then choosing accept This is useful for keeping track of which compilation errors have been fixed and which have not Page 9 icDelete from the Edit menu The starting point and ending point can be chosen from a num ber of alternatives For example the user can select some text by pressing down on the mouse and dragging The selected text will be highlighted To delete the text from the file and place it in the buffer set the from radio button to Start of Selection and the to radio button to End of Selection and then click on the accept button The text has now been removed and placed in a buf2. explanation of the various options The Flow menu Info Window This option brings up an external information window When any object is selected the calls made by and to that function are listed by line number This can be very useful when documenting code Restart This option will re load the call graph This option is a handy safety net if you get lost in a large call graph Page 15 The remaining diamond ought to contain the name of the directory from which field is running Double clicking for the rest of this section keep in mind that one only needs to click once if an object is already selected on this icon will bring up a diagram of how the files in that directory are linked together You are expanding your view of that directory One can also expand an object by choosing Expand from the Node menu In flowview elipses represent files Floview is now providing you with a diagram of how the C files in your directory are connected In this case our program is simple and only two files are involved Now double click on the counter C circle to bring up an expanded diagram of that file Double click on the elipse representing main C to expand that file as well Floview will show a diagram like the one in Figure 6 Boxes in flowview represent individual functions Rather than simply displaying the fact that main C contains a call to a function in counter C flowview is now displaying all the functions in counter C At thi
3. if you do not already have them open Make sure that the break option is highlighted in the Select menu of your editor Please see the FIELD User s Manual for information on the other available options Go to line 6 of main c and press the left mouse button down in the annotation column to the left of the source file A stop sign annotation should be placed in the annotation column See Figure 4 Starting Execution from Beginning of Program To begin running the program continuously from the begining of the program click on the Run button at the bottom of the debugger window The program should now ask you to enter the number of quarters in your pocket Type an integer followed by a carriage return in the debugger window below the prompt After entering the value the program should run until it hits the breakpoint that was set at line 6 of main c There should be an arrow annotation at this line in the source editor and a message in the debugger window saying that it stopped at the breakpoint Starting Execution after a Breakpoint To continue running the program again press the Continue debugger button The program will now ask you about the rest of the change in your pockets Clicking Run again will re start execution from the beginning of the program Executing Programs one Instruction at a Time After Run has been pressed and the program has stopped at the breakpoint at line 6 the debugger can now begin execution one
4. a call to the destination object The currently selected object is shaded in blue While you have a debugger session open for sorter click on the flowview icon A flow graph for the counter program should appear and look like Figure 5 O include CC You can use this diagram to navigate through your source code to animate your program s execution and to study the structure of your code The left mouse button will select an object and when clicked on a selected object it will alternately expand and compact your view of the calls made by and to that node in the graph The middle mouse button will display some basic information about any selected object The right mouse button will display an expanded list of the functions represented by the object In flowview a heaxagonal box represents a directory In your initial view the hexagon on the right represents the directory which includes the library functions cin and cout used in the sample program above Use the left mouse button to select the diamond on right and choose ignore from the node menu This tells flowview not to display calls to functions in that directory We are not interested in the structure of the C libraries and we have just expressed that to flowview Page 13 cause the debugger to execute the next line of the program and stop The arrow showing the position of execution will move down one line and the debugger will display a message noting the next li
5. it is convenient to replace all occurrences of a certain string with a different one To do so select the ReplceString option from the Edit menu Enter the pattern to search for in the Pattern field Enter the replacement pattern in the replacement field If one wants to replace only a certain number of occurrences of the string enter that number in the count field Click on Accept b Cutting text from a file A section of text can be removed from a file and held in a buffer The buffer text can then be placed in a new position by pasting the text Cutting text can be acheived by selecting Gener Page 7 double pennies cout lt lt How many pennies are in your pockets cin gt gt pennies pennies 01 change_ pennies cout lt lt You have lt lt pennies lt lt in pennies This leaves you with cout lt lt a total of lt lt change_ lt lt lt lt endl return change_ The Move Menu The following options represented by buttons in the Move menu can be used to quickly move the cursor through a file a Scrolling with the Scroll button You can move forward and backward in a file by pressing the mouse on the up arrow of the scroll bar to move up or the down arrow to move down Selecting the Scroll option from the Move menu will also scroll down one line To move greater distances hold down and drag the white box on top of the grey area of the scroll bar between the ar
6. IELD tools currently running This can save the user time if it becomes necessary to access lots of files in a directory different from the one that field was originally started from Policy Variables This brings up a simple dialog box with two options Auto Compile Page 2 FIELD Tutorial FIELD is a programming environment which integrates and provides graphical user interfaces for several tools in the UNIX environment It is designed to be used by students in computer science classes as well as programmers participating in advanced research projects The graphical user interface is easy to understand as well as configurable making it flexible enough for both beginning and advanced users This tutorial will give the programmer an introduction to some of the tools supported by FIELD and will demonstrate how to use those tools to develop software effectively by providing a step by step guided tour through the writing and debugging of a simple program Prerequisites It would be helpful if the user of this FIELD tutorial had a basic knowledge of the X window system and the UNIX environment including the following a how to create windows b how to use the mouse and keyboard as input devices in X c how to use various graphical user interface objects such as pull down menus dialog boxes scroll bars icons d how to write basic programs in C not required e how to manage programs with make to set up a Makefile Preparing
7. areful as FIELD will close the editors even if the files being worked on have been altered since the last save b the UNIX menu Shell This will bring up a new Unix shell which can be used to execute any shell command For example one could type pwd to find out what the current directory is Memory Info Does nothing at this time c the Windows menu Pop All This option will bring all currently running FIELD tools to the foreground Close All This option will close all currently running FIELD tools Again all the editors will be closed even if changes have been made since the last save Editing a File with FIELD FIELD provides the user with four different editing tools This tutorial will discuss the basic features that all the editors share For a more detailed description of the special features of each individual editor see the User s Manual Using the Aedit tool The aedit tool is a simple editor with none of the special annotation features shared by the other three editors This editor should be used when the user wants to create new files or modify old ones without using the other tools provided by FIELD Please refer to the User s Manual for more information on how the other editors can relate to the various FIELD tools The following discussion details how to perform simple text editing operations such as Cut and Paste To start aedit click on the aedit icon in the control panel the icon with the old Engli
8. e column to the right of the display Page 17 Trace Display Select this option if you would like flowview to animate the execution of your program Tracing Values of Variables with viewtrace The viewtrace tool allows the user to monitor the values of a variable Each time the variable is changed and program execution stops the viewtrace display is updated Open a debugger session on sorter Click on the viewtrace icon on the control panel Choose the Options button from the View menu A dialog box should ask for the name of the variable to trace Enter change_ in the Variable field of the dialog box and click on the accept button Ignore the error message Choose Run from the debugger buttons Each time you stop execution in a method of the ChangeCounter object the value of change_ will be displayed You can trace many variables from different objects all at the same time Displaying Object Strucure with the Class Browser The class browser provides the user with a detailed diagram of the program s object design Click on the cbrowse icon in the control panel Now move the mouse around until it is over the box representing the ChangeCounter class As in Flowview the name of the object the mouse is currently over will appear in the lower right hand corner of the cbrowse window You are now looking at a detailed representation of the only class of our example the ChangeCounter class Cbrowse displays all the objects used in y
9. e each time that line is reached In annotedit set the annotation type to trace by selecting the Trace button from the Select menu To place a trace at a line 7 of the program press the left mouse button in the annotation column to the left of the source code at line 7 of main c Now press the Run debugger button Each time the debugger executes line 7 it will print a message saying that it has reached that line This can be useful if you would like to check to see how often a line of code is executed without stopping exectution every time it is reached Removing Breakpoints and Trace Annotations Debugging annotations can be removed by setting the annotation type to the type of annotation that you want to remove and then clicking the left mouse button on the annotation or clicking the middle mouse over the annotation clicking on the remove box in the dialog box that comes up and then clicking on the accept button Other Commands Other commands are available for the debugger These commands can be entered at the ddt Page 12 through the next section to see how each option works If you are familiar with them already you may want to skip ahead Setting Breakpoints A breakpoint represents a line in the source file where the debugger will stop executing It can be used to stop the program periodically so that the status of variables can be checked and problem areas isolated Open counter c and main c in the editor you prefer
10. e from the Display menu of the list _head display The resulting linked list should look something like Figure ref final_var_disp For efficiency reasons the display graphics do not update themselves automatically but you can add update annotations at lines of code where the variable changes To do this open annotedit session on sorter c Set the annnotation type to UPDATE Click the left mouse button in the annotation column to the left of line 30 of sorter c Choose continue from the debugger buttons and enter values when the program prompts you The graphics display should update itself automatically after the new value is added to the list Appendix B Choose the Help button from the Commands menu of the Control Panel Figure help_window_top_level shows the help window that should be displayed The HELP Information tool of FIELD provides online documentation for the user The two paneled windows beneath the title HELP Information contain a list of the topics which online help documentation is available for The small window below the topics displays the name of the help information that is being currently displayed The scrolling window below that is the actual help information Click on control from the topics list to see the help for the Control Panel The help information for the Control Panel is divided into topics Each of these help topics represents a FIELD tool For other help information windows the topics describe the m
11. enu buttons or other features that are available Choose dbg from the topics list to see a description of what the debugging tool does Choose verbI control from the topics list to get back to the control panel help window Choose verbl lfield from the topics list to return to the field help window Displaying Program Stack with viewstack The program stack represents the function calls that a program has made As the program runs Page 18 representing count yello If the item is redefined in the child the children will color their lines in blue For example if the parent class has a virtual function called hello which is redefined by the children the children will color their lines blue when the parents line is selected This may seem a bit confusing so one should definitely load up a program more complex than counter and play around with these characterisitcs until they are well understood Once you understand what the various colors mean one can use cbrowse to get a detailed view of the class structure of large programs and one can frequently use it to track down errors made when coding class structures go over how colors are used in parents of selected items see meadow stuff for desciption of this Displaying Data Structures with typeedit and display FIELD can graphically display the values of variables This is especially helpful for viewing high level data structures such as linked lists and trees Displaying a Var
12. fer with the name in the buffer name field c Copying text from a file A section of text can be copied from a file into a buffer without removing the text from its original position To do this choose GenericPick from the Edit menu The dialog box is similar to the GenericDelete dialog box To copy highlited text into a buffer set the from radio button to Start of Selection set the to radio button to End of Selection and then click on the accept button d Pasting text into a file Text that has been cut or copied into a buffer can be inserted into the file by using the GenericInsert command from the Edit menu There are a number of options for the place ment of the text For example to insert the text in the buffer at the current cursor position set the where radio button to Current Postion and then choose accept The File menu a Saving a file A file can be saved to disk by using either the Savefile or Saveas command from the File menu 1 SaveFile saves the file to disk with the name that is shown in the message box at the bottom of the aedit window the middle name 2 Saveas writes the file to disk with a new name Choosing SaveAs from the File menu brings up a dialog box asking for the new name of the file Enter the desired name in the Name field of the SaveAs dialog box and choose the accept button b Quitting the editor One can quit from the editors by using e
13. for the Tutorial You will need to do the following things before you begin this tutorial a Login to a Sun workstation b Add the directory pro bin field to the path variable in your cshrc file To do this edit the file called cshrc with any editor On the line that says set path check to see if the directory pro bin field appears between the open parenthesis If it does not add the directory pro bin field just before the closing right parenthesis If you have modified the cshre file type source cshre in all shells This will tell the system that you have made changes to this file c Make a directory called field in your home directory by executing mkdir field from the Page 1
14. he o character Now the return key will cause blank lines to be added to the file Type in file main C include counter h main ChangeCounter counter new ChangeCounter double total counter gt quarters total counter gt dimes total counter gt nickles total counter gt pennies return 0 Type in file counter H class ChangeCounter private double change_ public ChangeCounter double quarters double dimes double nickles double pennies Type in file counter C Page 4 and EditingManyFiles If Auto Compile is set to True a compile will automatically start whenever a file is saved EditingManyFiles will temporarily disable the automatic compile so that the user can edit multiple files before the next compile To toggle between True and False just click on the appropriate red square Reload Resources This allows you to change the resources for any FIELD tool and to have those changes reflected the next time that tool is selected from the control panel This allows the user to quickly test configuration changes Environment This option allows the user to set any environment variable for all FIELD tools inlcuding both those currently active and those later used Quit This button allows the user to quit FIELD It will close all windows brought up through the control panel but will not effect any field tools that have been run independently Be c
15. iable with the display Tool Open a debugging session on sorter and add a few values to the list Press the Stop debugger button while the program is waiting for input to discontinue execution Choose display from the control panel A dialog box will appear asking for the name of the variable to display Enter list _head in the Variable field A picture similar to the one in Figure ref default_layout This is called the default display Changing How a Variable is Displayed with the typeedit Tool Click on the typeedit icon A dialog box should prompt for the type to be edited In the Type field enter struct list _item _t and choose the accept button A window similar to the one in Figure default_dis should appear Choose Default from the Top menu to see how the default view is displayed Choose Clear from the file menu to erase the default display and start a customized one Make the new display a tiled object by choosing Tiled from the Top menu This tells the editor that the C type can be represented as a rectangle divided into several different subregions called tiles Press down on the mouse in the upper left corner of the large rectangular white region and drag it to make a tile the width of that region Make another tile like it directly below The resulting view should look like Figure empty_tiled Click the middle mouse button in the upper tile to highlight it Choose box from the Edit menu and then click on the word value in th
16. ither the CloseFile or Quit command from the File menu 1 Choosing Closefile from the File menu causes the editor to automatically save the file and then quit 2 Choosing Quit from the File menu causes the editor to quit without saving the file If the file has not been changed the editor exits immediately If the file has been modified Page 8 cursor keys Parameters for Generichove basis Current Position Start of File End of File Start of Current Line End of Current Line Start of Selection End of Selection delta_lines 1 delta chars Accept Cancel c Searching for a string in a file using the GenericSearch button Often while programming it is helpful to be able to find all occurrences of a string in the program text To do this choose GenericSearch from the Move menu Type the string that you want to search for in the Pattern field of the resulting dialog box and then click on accept The cursor will be moved to the first occurrence of the string after the current cursor position Scrolling will occur if necessary To insure that all occurrences are found including the ones before the cursor select the wrap search radio button in the GenericSearch dialog box This will cause the search to continue from the top of the file if no occurrences of the given string are found before the end of the file The Edit menu a Replacing a string in a file When programming
17. line at a time Pressing the Step debugger button will Page 11 Making the Final Running Version Once you have gotten all your files to compile successfully you are ready to try to link them all together To do so choose MakeDefault from the Command menu Errors will be reported as they were when compiling Your code has successfully linked when the Result of Make box signals that the make was finished The debugger Now that your code has been compiled and linked it is time to try to execute it For this we will use the FIELD debugger The FIELD debugger is very similar to dbx on the Suns It has a window where commands can be entered with the keyboard buttons that can be clicked on for controlling the debugger and graphical breakpoint annotations that can be set in the annotedit annotddt or annotview editors It is very easy to add new buttons for commands that the user uses frequently To open the debugger click on the dbg icon on the control panel A dialog box and window should appear asking for the name of the program to debug Type counter in the Debug field and click on the accept button The debugger should start up and look like Figure 3 ddt 1 gt _ OCUS in routine main C main in file home frm field main C Executing Programs in the Debugger The debugger has several different program execution modes Some of the major options can be used by selecting one of the buttons that are on the botto
18. m of the debugger window Work Page 10 FIELD puts up a dialog box asking the user to confirm that the file should not be saved If the Ignore Changes radio button is set and the accept button chosen the file will not be saved If the Save button is set then the file will be saved before quitting aedit The default button is Ignore Changes Note Many of the function keys have special meaning in aedit These meanings are docu mented in the Brown Workstation Environment manual Compiling and Linking Files The annotedit tool is an editor like aedit but it has additional capabilities like allowing the user to mark the lines of a file with graphical symbols or annotations for compiling and debugging To compile counter c click on the annotedit icon on the control panel A dialog box should appear asking for the name to the file to edit Type counter c in the Name field of the dialog box and click on the accept button To learn more about the addtional menus and options available with this editor see the FIELD User s Manual Compiling your code Choose compile from the Commands menu A thin message bar should appear saying that it is compiling your file After the compilation is done a dialog should display any compilation errors Click the accept button on the dialog box when you are finished reading the error messages A thumbs down will appear to the left of any line containing an error A box with
19. ne to be executed If the line of code is a function call as it is in our example the debugger will stop at the first line of code in the called function The editor with counter c in it will also move the cursor to that line To avoid jumping into that function as we must do now to avoid jumping through all the code for the cout operator press the Next button Rather than stopping at the next line of code the debugger will stop at the next line of code that is within the current function Stopping Execution If the debugger is executing a program and you would like to halt it but there is no breakpoint set press the Stop debugger button The debugger will display a message telling what line it stopped on This feature is useful for breaking out of infinite loops One can then step through the code to find the problem The Kill button will end the current execution cycle entirely meaning that the user would not be able to continue to step through code once it has been pressed Printing the values of Variables The debugger allows you to see the value of variables While the debugger is stopped select the name of a variable in the current procedure by using the mouse to highlite it in one of the editors or in the debugger Now press the Print It debugger button This will print the current value of the variable in the debugger window Tracing Placing a trace at a line in the source will cause the debugger to print out a messag
20. on on any box will bring up a list of all the functions represented by that box The left mouse button compacts the view Floview will also animate the execution of your program Click run in the debugger The box representing main C in the flowview display will turn red As the program executes flowview will display in red the function currently being executed The following is an abbreviated list of some of the menu options available with flowview The Node menu Ignore Will remove the selected object from the call graph Expand Will expand the view of the selected objects Basically it will show a more detailed break down of the calls made by that object by moving one level ahead in the object heirarchy For example expanding the view of a directory will display the connections between the files in that directory Expanding a file will display the functions in that file Compact Will compress the view of the selected objects It will undo the actions of Expand Show Info Will have the same effect as clicking the middle mouse button on a selected object A dialog box containing a brief description of the nature of the object will be presented to the user The Display menu Options Allows the user to select how objects are displayed in Floview For example selecting the Expand size to show text option will get flowview to expand the size of any selected object to make its name legible See the Uswer s Manual for a more detailed
21. our program and shows you how they are related It also provides the user with a detailed graphical image of the individual classes themselves Each line in the box representing the ChangeCounter class contains the name of either a member function or of an instance variable The variables are listed at the top of the box and are demarcated by the triangle pointing to the left on the side of the box Functions are marked by a triangle pointing to the right The triangle is solid if the member is private clear if it is public and shaded if it is protected If you click on any line with the right mouse button cbrowse will use colors to show how that item is defined throughout the class structure The item selected will be marked green If is an item that is inherited by other objects the line representing that same item in all the related classes will be colored as well In all children classes lines will be colored yello if the child does not modify that item For example if the parent class has an integer count and you select the line representing count in cbrowse all the children will color in the line they have Page 16 some attributes of all the functions in your program Clicking on any box in flowview with the middle mouse button will bring up a box containing information on that function The box will tell you where the function is defined how many functions call it and how many functions it calls Clicking with the right mouse butt
22. rows Move the white box up to scroll backwards and down to move forwards b Moving the cursor with the GenericMove button The cursor can be moved by clicking the mouse in the desired location or by choosing the GenericMove command from the Move menu This will bring up a dialog box like the one in Figure 2 It asks for the point to start moving from and the number of lines and characters to move For example to go to the beginning of the 5th line of the file choose Start of File as the basis and set delta_lines to 5 and delta_chars to 0 This will move the cursor five lines and zero characters beyond the start of the file This option is particularly helpful when the user wants to move to a specific line in a large file The cursor can also be moved by using the arrow Page 6 include counter H include lt iostream h gt ChangeCounter ChangeCounter change_ 0 double ChangeCounter quarters cout lt lt How many quarters are in your pockets cin gt gt change_ change_ 25 cout lt lt You have lt lt change_ lt lt in quarters lt lt endl return change_ doubel ChangeCounter dimes double dimes cout lt lt How many dimes are in your pockets cin gt gt dimes dimes 1 change_ dimes cout lt lt You have lt lt dimes lt lt in dimes This leaves you with cout lt lt a total of lt lt change_ lt lt lt lt endl re
23. s point you have a complete diagram of how your program executes main C calls five functions in the file counter C Flowview is a very powerful and helpful tool Spend some time using the mouse to navigate around flowview until you fully understand the effects of your actions and what the various shapes represent If the text within the shapes is hard to read simply move the mouse over any one you are interested in Then name of what that shape represents will appear in the lower right hand corner of the flowview window Now open the annotddt editor or the annotview editor and bring up the main C file If you click once with the left mouse button on any of the boxes in flowview that represent a function in the program counter the editors will automatically move the cursor to the beginning of that function When dealing with large programs that involve many files and hundreds of functions this option can prove to be a major timesaver One can also save time when documenting code by using flowview as a quick reference on Page 14 prompt Read the dbx manual page for more information about the complete set of commands or type help in the debugger to see a partial list Other FIELD tools Displaying Program Structure with flowview The flow tool will automatically produce a directed graph representing the procedure calls in the program A node in the graph represents an object and an arc represents that the source object contains
24. sh E A dialog will prompt you for the name of the file to edit In the File Name field type counter c and click on the accept button for now ignore the System field The current contents of the file are displayed Since counter c is a new file the window should be empty Page 3 shell d Enter the new directory by typing cd field Getting into the FIELD environment To start FIELD simply type field in a shell The Control Panel window like the one in Figure 1 will be placed on the screen The Control Panel Window The FIELD Control Panel gives you access to all the tools available in the environment Each tool is represented by a lettered icon and can be opened by clicking on that icon Online FIELD help a UNIX shell and some other options can be accessed from the menu bar The following is a brief description of the various options available from the menu bar a the Commands menu Help This button brings up a help screen which can be used to get a brief explanation of what the various tools are capable of See Appendix B for more on this Mouse Help This option allows the user to check what the mouse buttons do in different windows For example if the user moves the mouse into the Help window the functions of the mouse in that window will be displayed in the Mouse Help window Refresh Executes an XRefresh on all windows Directory This option allows the user to set the working directory for all the F
25. the stack display will automatically update itself Click on the viewstack icon from the Control Panel A window similar to the one shown in Figure ref viewstack1 should appear Set a breakpoint at the first line of the function main Choose run from the debugger buttons to execute until the first breakpoint The stack viewer should have been updated and the new view should look like Figure viewstack2 Each function call entry on the stack is offset by a number representing the stack level The highest number appears at the top of the screen and represents the current procedure that is executing Each stack entry also includes the parameters to the function in parenthesis and the line number and source file that the function is defined in followed by a list of the values of any local variables Choose step from the debugger buttons and an entry in the stack should be produced for the function call to create _new _item The stack will continue to be automatically updated as the program runs Mention that individual tools can be used io e flowview counter Page 19 Click the middle mouse button in the lower tile to highlight it Choose Pointer from the Edit menu and then click on the word next in the column to the right of the display The window should now look like Figure finished_edit Save the new display for the linked list by choosing Save from the File menu To make the display window reflect the new display method choose Updat
26. turn change_ double ChangeCounter nickles double nickles cout lt lt How many nickles are in your pockets cin gt gt nickles nickles 05 change nickles cout lt lt You have lt lt nickles lt lt in nickles This leaves you with cout lt lt a total of lt lt change_ lt lt lt lt endl return change_ double ChangeCounter pennies Page 5 Adding text Adding text in the field editor is simple Just type the letters from the keyboard When you want to go to a new line simply press the return key Notice that when you hit return after typing main the cursor is indented on the next line This is the auto indenting feature of the FIELD editor It helps the user format code quickly and easily by automatically indenting the start of a new line to a position that helps define distinct code blocks The rest of this section describes how to perform a number of editing functions Please experiment with these functions as you use aedit to create the following C program Note If you get an error stating that a file is readonly you can use the F8 key to toggle out of the readonly mode Note If you hit the return key when the cursor is not at the end of the file you will notice that blank lines are not added to the file Putting the editor in Open mode will make it so that the return key adds a blank line to the text To do this press the control key and then t
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