[ python-Feature Requests-1612190 ] Py_DEBUG

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Feature Requests item #1612190, was opened at 2006-12-09 16:48
Message generated for change (Comment added) made by loewis
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: nitro (nitrogenycs)
Assigned to: Nobody/Anonymous (nobody)
Summary: Py_DEBUG

Initial Comment:
Hello,
 
I am writing an extension module (Win32, VC8). Of course I need to #include <Python.h>. Now, when _DEBUG is defined in my application Py_DEBUG gets defined as well (in pyconfig.h). I don't want this to happen as I have to link to the python debug library that way. However, I don't want to debug python, I only want to debug my own application. So the automatic definition of Py_DEBUG doesn't seem right. A solution that would be backwards compatible could look like:
 
#ifdef _DEBUG && !defined(Py_NO_DEBUG)
#	define Py_DEBUG
#endif
 
Could something like this be included in python? Note that #undef _DEBUG #include <Python.h> #define _DEBUG does not work as VC8 complains in this case, because some header files had the _DEBUG preprocessor symbol and some didn't. That trick used to work in VC 6 and 7.x. I've seen a lot of people fighting this problem.
 
Another problem that also arises from pyconfig.h is this code:
 
#			ifdef _DEBUG
#				pragma comment(lib,"python24_d.lib")
#			else
 
I don't think it's clean that python tells my program what to link to. I am the one who should (and wants to) do this via a linker switch. I know that some people probably would regard the code above as a feature, but it's the opposite imo. A backwards compatible change could look like:
 
#ifdef MS_COREDLL
#	ifndef Py_BUILD_CORE /* not building the core - must be an ext */
#		if defined(_MSC_VER) && !defined(Py_NO_AUTOMATIC_MSVC_LINK)
			/* So MSVC users need not specify the .lib file in
			their Makefile (other compilers are generally
			taken care of by distutils.) */
#			ifdef _DEBUG
#				pragma comment(lib,"python24_d.lib")
#			else
#				pragma comment(lib,"python24.lib")
#			endif /* _DEBUG */
#		endif /* _MSC_VER */
#	endif /* Py_BUILD_CORE */
#endif /* MS_COREDLL */

Thanks,

-Matthias

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>Comment By: Martin v. Löwis (loewis)
Date: 2006-12-11 20:09

Message:
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You should just not define _DEBUG then. You don't need to define _DEBUG to
perform debugging; instead, _DEBUG requests that the debug version of the
MS CRT is linked to your application.

As mixing different CRTs (e.g. debug and non-debug) in a single
application can cause crashes, you *must* use a python2x.dll that is linked
with the debug CRT; this will be python2x_d.dll. So no, something like this
should not be added to Python.

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