The C++ Debugging Support Library

Tutorial 4: Management of CWDEBUG

In a production environment you most likely want to remove all debugging code from the application because it makes the application slower, of course.  You can do this by compiling the final application without defining the macro CWDEBUG.  You also don't need to link with libcwd in that case.

In example, with debugging code you'd compile a program as

g++ -g -DCWDEBUG -lcwd -o application

and without debugging code you'd use

g++ -O3 -o application

Because the final application doesn't need libcwd, we can afford to use features of g++ and third party libraries that developers are able to install but that would be impractical as demand for the end-user of the application.  The developer that uses libcwd will have to use g++ as compiler and perhaps use a linux box for the development of the application, but gets a lot of developing advantages in return.  Afterwards it is relatively easy to port the bug-free code to other platforms/compilers.

As a developer you need to know two things:

  1. How to compile the application you are developing, while you're still developing it.
  2. How to compile a final version of your application, without debugging support.

In the first case, all libraries and your application need to be compiled with CWDEBUG defined.  In the second case all libraries, except libcwd (because you won't link with it) and your application, need to be compiled with CWDEBUG undefined.

Libraries that do not use libcwd (or otherwise depend on the macro CWDEBUG) do not need to be recompiled of course.  If you are writing an end-application and do not have other libraries that depend on libcwd (or otherwise depend on the macro CWDEBUG) then it is as easy as defining CWDEBUG and linking with libcwd, or not defining it and not linking with libcwd.  However, if you are using other libraries that depend on or use libcwd, then these need to be recompiled too before linking with them.  If you are writing a library yourself then at least distribute a version without debug support, but consider to also release a developers version with debug support turned on.  Realize however that the meaning of the macro CWDEBUG is: debugging the application that is developed with a library, not debugging the library itself! Testing a library is best done with seperate test applications.  If extra debugging code is needed to test the library itself then use a library specific define like DEBUG_YOURLIB.

Finally, in order for others to be able to compile your application without having libcwd installed, you need to include a custom "debug.h" and "sys.h" as is described in chapter Preparation of the Reference Manual and in tutorial 2.

Copyright © 2001, 2002 Carlo Wood.  All rights reserved.