[python-win32] mxDateTime problem with embedded Python

[Will Sadkin]

Hi all,

I have a bit of a stumper.  We have a C++ program in which we embed a
release python interpreter, so that both our C++ and python programs can
share a single codebase, written in Python.  When building the program
for debug, we always #undef _DEBUG while including Python.h, and always
therefore link with python27.lib, and embed the *release* interpreter.
(We did this so that we don't have to locate and/or build debug versions
of the python interpreteter or extension dlls we may load (eg pyodbc,
mx, etc.  At least that was the theory.))  

This embedded interpreter ends up importing a python package that tries
to run the line:

    from mx import DateTime

>From within the release C++ executable, this works just fine.  But with
the debug executable, it generates the following exception on that line:

    DLL load failed: A dynamic link library (DLL) initialization routine
failed.

I have a hypothesis as to why this is happening, bug am not sure how to
confirm it, nor what to do about it.  
I suspect that the python27.dll is a statically linked dll, and so the
embedded python interpreter I create can run on its own, regardless of
the rest of the dlls linked into the rest of the executable.  (This
would be the only way I could see this working at all.)  However, the
executable containing that release Python interpreter is still linked
with the debug Microsoft dlls to allow debugging, and I suspect that the
(release) mxDateTime extension pyd is NOT statically linked, and so when
it attempts to load within the embedded framework, it can't because one
of the release DLLs *it* depends on (probably MSVCR90.dll, judging by
the output from depends.exe) is not linked into the executable and/or
conflicts with the MSVCR90D.dll that already is.

As I said, I'm not sure how to confirm this, nor what to do about it,
and I'm hoping Mark Hammond may have some suggestions.
I have a different bug in this program that I really need to track down
in the VS2008 debugger, but I am stymied because this problem occurs
before I can get to the code in question, and so the program doesn't run
the same way in both release and debug versions.

Thanks in advance,
/Will Sadkin
Parlance Corporation