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Symantec Top 10

This monthly column, written by Symantec’s Technical Support Engineers, aims _to provide you with technical information based on the use of Symantec products.

By Levi Brown, Symantec Corp.

Q: I set my project’s preferred and minimum memory partition sizes in the “Project Type” window, but when I build my application, the preferred and minimum memory partition sizes are always set to a different value. What is wrong?

A: The project’s resource file contains a SIZE resource that always overrides the value set under the Project, Options..., “Project Type” window. To solve this problem, open the ProjectName.rsrc resource file with ResEdit and delete the SIZE resource.

Q: I have heard of this program called Discipline that works with MacsBug to provide a higher level of error checking. What does it do, and does it work with the Symantec Debugger?

A: Discipline is a system extension that works with MacsBug to check the arguments passed to Toolbox routines. Discipline is built into MacsBug 6.5d12. To access it, you use the dcmd dizy.

Our debugger has not been tested thoroughly with Discipline. Therefore, it is possible that you may run into some incompatibilities. Discipline has a habit of revealing problems with many different programs including the Finder, which makes it difficult to use as a debugging tool.

Q: In UNIX there is a collection of routines, declared in curses.h that can be used to manipulate the cursor in a console-like display. In my Symantec C++ 8.0 project using the console window how can I achieve similar results?

A: Most of the functionality of the console window is declared in console.h. Here is an example of how to move the cursor to a specific point, and clear everything in the window from that point down.

#include <stdio.h>
#include <console.h> 

main()
{
 int i, ch, rows = 12, cols = 40;

 console_options.nrows = rows;
 console_options.ncols = cols;
 cshow( stdout );
 csetmode( C_NOECHO, stdout );
    // Set mode to C_NOECHO, so
    // getchar doesn’t move the
    // cursor.
 for( i=0; i<rows*cols; i++ )
 putchar( 'x' );
 cgotoxy( 5, 3, stdout );
 ch = getchar();
 ccleos( stdout );
}

Before the call to ccleos()

Q: I’m using the ToolBox call GetPicture() and I want to clean up the memory after I am done with the picture. How do I do that?

A: Pass the handle that GetPicture() returns to ReleaseResource(). Do not call DisposeHandle() on a handle to a resource or you may corrupt the resource map.

Q: When I try to use the QuickDraw global variables in my Symantec C++ 8.0 project I get undefined symbol errors. I’ve used the same globals many times before using 7.0 and it worked just fine. What is happening here?

A: With the introduction of Apple’s Universal Headers, access to the QuickDraw globals changed. Your 7.0 project was probably referring to the QuickDraw globals in the “old” style and using the original header files, not the Universal Headers. You will need to access the QuickDraw globals through the qd struct, defined in Quickdraw.h. i.e.:

CopyRgn(thePort->visRgn, thePort->clipRgn);

would become

CopyRgn(qd.thePort->visRgn, qd.thePort->clipRgn);

Q: I have a large 8.0 project with many files and I frequently use the Find... command under the Search menu. Every time I use it I have to set up the find parameters each time. Is there a way to set default search parameters?

A: Yes! In your Symantec C++ folder there is a folder called (Scripts), inside which you will find a compiled script called Startup:

tell application "Symantec Project Manager"
 -- Set the default search state.
 set user search state to ¬
 {wrap around:true, ¬
  ignore case:true, ¬
  files to search:only sources, ¬
  exclude system:true, ¬
  exclude precompiled header:true}
end tell

You can set the default parameters for the find in the indexed list shown above.

Q: I get link errors with a class that has static data members. Why is this?

A: If you declare a class with static data members you need to initialize those data members in the global data space outside the class, so that memory is allocated for them. If you do not initialize the static variables in global data space outside the class then the compiler does not have a location for the static data members in memory. Thus, you get a link error when you attempt to access that variable. Example:

class A
{
public:
 static short x;
 static char  y;

 char z;
};

short A::x = 0;  // Note: These variables are initialized
char  A::y = 'a';// outside the class declaration in
    // order to allocate memory for them.

Q: The following code used to work (up through 8.0), but in 8.0.1 it doesn’t. Why?

class A
{
 friend class B;
public:
 A();
 ~A();
 B *GetFriend(int index);
};

class B
{
public:
 B();
 ~B();
 int index;
};

I get an error on line 7 “semicolon expected”. If I put friend before B *GetFriend(int index), it works. Is it a compiler bug, or is it a new ANSI rule of some kind that I didn’t know about?

A: A couple things are happening here:

First, the code above compiled in previous versions due to a compiler bug. 8.0.1 corrects this error. Basically, the syntax is wrong. The class A has no idea what B is yet, and thus the compiler complains. If you put a forward declaration, class B;, in front of the declaration of A this will compile fine.

Second, the statement friend B *GetFriend(int index) tells the compiler that GetFriend is a friend function, and therefore has access to A’s protected and private members. The statement B *GetFriend(int index) tells the compiler that GetFriend is a member function of A. In both cases the friend class B does nothing more than allow all members of B access to A’s private and protected members.

Q: I have made a floating window view in Visual Architect, but when I go to attach it to a command, it does not appear in the list of views to open. How do I open it?

A: When you make a floating window view, VA derives a class from CFloatDirector; we will call it CMyFloatingWindow. You need to call OpenWind() to make the window appear (ShowWind() only undoes a HideWind()). The easiest way is to call it from within CMyFloatingWindow::MakeNewWindow(), right after the object is created; the window will appear immediately upon launch. To have it open from a command (i.e. menu or button), create the command by choosing Commands... from the Edit menu in VA. Enter the name for your command (e.g. cmdOpenMyFWindow), choose CApp from the In Class: popup menu and choose Call from the Do: popup menu.

Next, attach the command to the menu or button. If attaching to a menu: choose Menus... from the Edit menu, select the menu, click on Edit Menu Items, select the item and choose the command you created from the Command: popup menu. If attaching to a button: select the button in VA, get Pane Info from the Pane menu, open the CButton triangle and choose the command you created from the Command: popup menu.

Visual Architect will generate an empty function, DocmdOpenMyFWindow inside x_CApp.cp. Call OpenWind() from here.

Note: Calling from outside the CMyFloatingWindow requires that you have a pointer to the CMyFloatingWindow object. You can find this declared as a global in x_CApp.cp in the form:

 extern CAFloatingWindow  *gCAFloatingWindow; 

If you wish to make the call to OpenWind() from someplace other than x_CApp.cp, you must redeclare it (as above) and #include CMyFloatingWindow.h in the file where you want to use it.

Q: When I try to run the Symantec Debugger it quits with an error that says, “DebugServices cannot set trace bit.” How do I set the trace bit? I can’t find any options to set a trace bit in any of the project option debugging screens.

A: Most likely, you are running a Pre-System 7.5 operating system. You will need to put the items that are in the Pre-System 7.5 Additions folder into your system folder. The Pre-System 7.5 Additions folder is found in the Apple Software folder on your Symantec C++ 8.0 CD-ROM.

Bonus:

Q: I’m porting my code from 7.0.x to 8.0 and I get an “undefined symbol MBarHeight” when I try to compile. Why do I get a linker error?

A: With the introduction of Apple’s Universal Headers you can no longer access the variable MBarHeight directly. You will need to include LowMem.h and use LMGetMBarHeight(), and LMSetMBarHeight(), to access menu bar height. Access to other low memory variables has been changed in similar ways, so it’s a good idea to look in LowMem.h if you plan on using low memory variables.

Special Thanks To:

Glenn Austin, Mark Baldwin, Craig Conner, Rick Hartmann, Michael Hopkins, Steve Howard, Noah Lieberman, Andy McFarland, Chris Prinos, and Kevin Quah.