Think Top 10

By Mark B. Baldwin and Michael Hopkins, Symantec Technical Support

Q. Can I use the Think Class Library in a CODE Resource?

A. In case you haven’t noticed, CODE Resources are finicky. The TCL uses virtual functions, and the virtual table uses global data space. Using global data space is upsetting to the discriminating palette of CODE Resources which use A4. You can, however, use your own classes that do not use virtual functions. If you decide to do this, you must turn on the Multi-Segment option.

Q. When I run Profiler, why do I get an internal error in PC.H?

A. This is a bug. When you run Profiler, turn off “Use function calls for inlines”, under the options for the C++ compiler, in the compiler options window.

Q. Why is a CArrowPopupPane arrow not drawn in the center of the pane?

A. The horizontal setting is incorrect in the Draw () routine. The trick is to set the field sicnPt.h to 0;

/* 1 */
void CArrowPopupPane::Draw(Rect *area)
{
Point sicnPt;
sicnPt.h = 4;   // set this to 0;
sicnPt.v = 7;
DrawSICN(TCL_SICN, POPUP_SICN, sicnPt);
CPopupPane::Draw(area);
}

Q. Why do derived classes of ifstream cause a bus error when they read in a stream?

A. Any class indirectly derived from the virtual base class ios needs to explicitly call the ios constructor to initialize the buffer into which the data stream is read. For example:

/* 2 */
class myifstream : public ifstream {
myifstream(char * s) : ios(&buffer), ifstream(s){} }

Q. When I create a text file using ofstream, why can’t Mac word processors open the file?

A. In order for a word processor to recognize the text file, the file must have a recognizable file type and creator. First, you will need to include stdio.h. Second, you will need to initialize the globals _ftype = 'TEXT' and _fcreator = 'ttxt' before creating the text file. For example:

/* 3 */
#include <stdio.h>
#include <fstream.h>

void main(void) {
FILE *fp;
_ftype = 'TEXT';
_fcreator = 'ttxt';

ofstream textfile ("foo.txt",ios::translated);
textfile << "This is a test" << endl;
textfile << "This is line 2\nThis is line 3\n";
textfile.close();
return 0;
}//end main

Q. Why do I get incorrect values for floats when I have the 68881 options on?

A. When you set the 68881 compiler options for your project:

• open all the libraries

• the libraries and the project must have the same options set

• bring the project up to date

Don’t forget the unix++ library that is in the IOStreams library.

Q. I am using the example in the manual for using the #pragma parameter as part of the process of locking a CODE Resource. Why do I get the error that a prototype is required?

A. The first statement generates an error. The second statement should resolve this error.

/* 4 */
#pragma parameter __D0 RecoverResPtr()
Handle RecoverResPtr() = 0xA128;   //generates error

#pragma parameter __D0 RecoverResPtr(void)
Handle RecoverResPtr(void) = 0xA128;    //resolves problem

Q. When I am using the debugger to debug my program when the project, project files, and debugger are not all on the same machine, why do I get a message in the debugger, "Out of memory" ?

A. The debugger was not originally designed to work on remote files. The source files will have to be on the same machine as the project file and Debugger.

Q. I am using MacApp with SC++ for MPW. The MacApp documentation states that I need to rebuild the Symantec Libraries with model -far. How do I do this?

A. You should be able to compile most MacApp projects without modifying the SC++ libraries. However, if you really want to rebuild the libraries, follow these steps:

• Go into the folder :MPW:Libraries:SCLibraries:SCSrcLibCpp and change SCLibCpp.make from: COptions= -r -O all -sym on AOptions= -case on to: COptions= -r -O all -sym on -model far AOptions= -case on -model far

• Remove the precompiled header file IOSMacDefs in :MPW:Libraries:SCLibraries:SCSrcLibCpp:IOSMacDefs

• If they do not exist, create the folders SCppObj and SCObjpp881 in :YOURHD:MPW:Libraries:SCLibraries:SCSrcLibCpp

• Do a build of SCLibCpp. Repeat the process with SCLibCpp881.make and do a build of SCLibCpp881.

Q. When I create a TCL application, is there any particular way that I need to segment my project?

A. You can segment your application in any fashion, but certain libraries must not be purged. These files and libraries must be in a resident segment:

/* 5 */
CApplication.cp  TCLUtilities.cp   TCLpstring.cp
Exceptions.cp    CPlusLib MacTraps2
LongCoordinates.cp MacTraps

As delivered, the VA project model and the demos have MacTraps and MacTraps2 in purgeable segments. This is because these projects don’t contain any code that would ever unload these segments. If your code does any loading or unloading of segments, make sure that you change the MacTraps segment so that it is not purgeable.

Special Thanks To

Craig Conner, Colen Garoutte-Carson, Rick Hartmann, Steve Howard, Celso Barriga, Kevin Irlen, Yuen Li, and Scott Shurr.