Jan 95 Top 10
|Column Tag:||Think Top 10
Think Top 10
This monthly column, written by Symantecs Technical Support Engineers, aims to provide you with information on Symantec products. Each month we cover either a specific application of tools or a Q&A list.
By Craig Conner and Rick Hartmann, Symantec Technical Support
Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.
Q: Why do I get a bus error when I try to use the VIA timer option for the profiler?
A: The Symantec C++ 7 documentation states that the profiler uses the VIA (Versatile Interface Adapter) timer which ticks every 1.28 microseconds. If you want to use Ticks (1/60 of a second), modify the profiler code to do so. Not all Macintosh models contain a VIA timer chip. To find out if your Mac has a VIA timer chip, you should use the functions gestaltHasVIA1 or gestaltHasVIA2 (Mac II).
If you have the chip, modify profile.c as follows:
#define Ticks VIA_Ticks()
#define Ticks LMGetTicks()
Next, remove all of the #ifdef __CONDITIONALMACRO__ statements in profile.c, then use the Ticks assignments.
Q: Why cant I use fopen to open more than 12 files?
A: stdio.h defines a table for keeping track of open files. This table is defined as:
extern FILE __file[FOPEN_MAX];
where FOPEN_MAX is declared as 15. Three streams are reserved for stdin, stdout, and stderr which leaves 12 more for you to use. To open more than twelve files, increase the value of FOPEN_MAX and recompile the ANSI library. Alternatively, you can use Macintosh Toolbox calls to open files; those files are not counted against the limit.
Q: When I try to use TESetWordBreak I get a link error.
A: Below is an example of how to use TESetWordBreak with the current Universal Headers. The changes only apply to 68K use. You can use TESetWordBreak directly when compiling for PowerPC. Basically the problem is that Apple doesnt provide the glue for the new routine name, but has written the Universal Headers as if they did. [This was fixed on ETO #15. Interface.o on ETO #15 has an extra entry point added for TESetWordBreak. There was also the same problem and fix for SetClikLoop -> TESetClickLoop - Ed stb]
// Need to undo the redefinition of SetWordBreak in the Universal Headers when in
// 68K. Glue for SetWordBreak is in MacTraps, but there is no glue for
// TESetWordBreak. We also need to redefine any calls using the new name
// for the same reason
extern pascal void SetWordBreak(WordBreakUPP wBrkProc,TEHandle hTE);
#define TESetWordBreak(wBrkProc, hTE) SetWordBreak(wBrkProc, hTE)
pascal Boolean myWordBreaker(Ptr textPtr, short offset );
WordBreakUPP brk = NewWordBreakProc(myWordBreaker);
// either of the following two are ok
pascal Boolean myWordBreaker(Ptr textPtr, short offset )
if (textPtr[offset] == 's' )
Q: How do I use new to obtain a two dimensional array?
A: Each row element in a two dimensional array is actually a pointer to the row. To access a two dimensional array using new, you need to tell the compiler that you want two dimensions like so:
int (*intarr) = new int;
Then you can access the memory using array references, e.g. intarr.
Q: Do I have to declare objects as volatile in TRY/CATCH macros?
A: Yes. When a TRY is executed, all registers are saved. When CATCH is executed, the registers are restored to the saved state. If you change a value of a non-volatile variable within a TRY block, its possible that the value will be restored to what it was before the TRY when the CATCH is triggered. If you use a volatile variable, the compiler forces its value to be saved to memory any time its changed, and wont let it be cached in a register.
Q: Do I need to recompile the ANSI++ library with 8-byte doubles to use it in a Visual Architect project?
A: 8-byte doubles are no longer required for VA (or other TCL) projects. The default VA project still ships with 8-byte doubles on while the ANSI++ library ships with it off. It is ok to turn this option off in your TCL projects.
Q: How do I trap CRadioControl commands within a dialog?
A: By default the values of radio buttons are not verified until a dialog box finishes the DoModalDialog() function. DoModalDialog returns a command of type long. At this point, the programmer should create a switch statement where the values of radio buttons are checked with the (CRadioGroupPane*)FindViewByID->GetStationID(theRadioDITL) method.
The problem with this style is that the values of the radio buttons are obtained after the dialog is dismissed. Often, the programmer will want to have the changing values of radio buttons change the characteristics of items in the dialog itself. For example, a programmer may want the font of a CDialogText to change according to the settings of radio buttons.
The solution has three parts.
1) Set up your derived CDLOGDirector class so that it owns the CRadioControl pointers. This will give you access to the radio buttons throughout your class.
2) When you instantiate CRadioControl make a call to SetClickCmd(). Make sure to set each button with its own command. For the command to work, it must be something other than zero.
3) Add a DoCommand() function to your derived CDLOGDirector class.
myDialogText->SetTextFont(3); //Set font to geneva
myDialogText->SetTextFont(0); //Set font to chicago
The default statement is extremely important for this construct. The inherited DoCommand() is trapped by CDialogDirector to process the OK and Cancel command. If you do not trap these commands yourself, or do not have an inherited method trap them, you will not be able to dismiss the dialog.
Q: In Visual Architect, can I have main windows that are not based on CSaver?
A: In Visual Architect 7.0.4, the code generation does not recognize the checkbox for the Use File option. The solution is to change the code in the GenerateTCLApp VA template file for documents, as follows:
$elseif class.basename == "CDocument"$
$generate "Source:$class.name$.cp" "Doc_cp" once$
$generate "Source:$class.name$.h" "Doc_h" once$
$generate "Source:ItsContents_$class.name$.h" "ItsContentsClass_h"
$generate "Source:CSaver_$class.name$.cpp" "CSaver_class_cpp" once$
$define do_document 1$
Q: How do I change the font attributes in CStdPopupPane?
A: Changing the font of popup menus is not intuitively obvious. The process involves several steps.
1) Create a menu resource with a title and a menu item. Remember its ID number.
2) Instantiate your CStdPopupPane.
myPopUp = TCL_NEW( CStdPopupPane, (menuID, itsWindow, this,
0,0, 100,100, TRUE, FALSE, FALSE));
3) Make sure to #include CTextEnvirons. Then create a local pointer to a TextInfoRec, and fill the struct with the text information that you want in your popup.
TextInfoRec * myTextInfo = new TextInfoRec;
myTextInfo->fontNumber = 10;
myTextInfo->theSize = 12;
myTextInfo->theStyle = bold;
myTextInfo->theMode = qd.thePort->txMode;
4) Cast the itsEnvironment member of the CStdPopUpPane as a CTextEnvirons, allocate memory for it, and call the SetTextInfo() method.
TCL_NEW (CTextEnvirons, (FALSE));
5) Dont forget to delete the temporary variable myTextInfo.
Q: Visual Architect projects take so long to compile. How can I reduce the compile time? (Reprise)
A: In Octobers Think Top 10 we had a question concerning saving time when using VA projects. The answer we gave was to compile the @1.Π file in the Visual Architect Project Model. The problem with that is that the debugging information doesnt get copied when you create a new project.
To avoid that problem, before you compile, uncheck the Store Debug Info Separately switch in the debugger options for the Think Project Manager. This will store the debug info inside of the project file, so that it will be copied into your new project. If you wish, you can uncheck the switch after creating your project; it wont force a recompilation.
Thanks to Michael Hopkins, Mark Baldwin, Steve Howard,
Phil Shapiro, Rich Parker, and the rest of the gang.