building a python module on windows using ms compiler

Question

I am trying to build the example that comes with the source distribution of python under PC\example_nt

I copied example.c and setup.py to a directory C:\mymod

When I run C:\Python27\python.exe setup.py install I get the error....

error: Unable to find vcvarsall.bat

I did some digging around in distutils and saw that it was going after version 9 of microsoft visual studio but I only have version 8. Apparently it tries to get version 9 because of what the python under C:\Python27 was compiled with.

I modified setup.py and put the following at the very top.

from distutils import msvc9compiler
msvc9compiler.VERSION = 8.0

After doing this I was able to compile and got the following....

C:\mymod>C:\Python27\python.exe setup.py install
running install
running build
running build_ext
building 'example' extension
creating build
creating build\temp.win32-2.7
creating build\temp.win32-2.7\Release
C:\Program Files\Microsoft Visual Studio 8\VC\BIN\cl.exe /c /nologo /Ox /MD /W3
/GS- /DNDEBUG -IC:\Python27\include -IC:\Python27\PC /Tcexample.c /Fobuild\temp.
win32-2.7\Release\example.obj
example.c
creating build\lib.win32-2.7
C:\Program Files\Microsoft Visual Studio 8\VC\BIN\link.exe /DLL /nologo /INCREME
NTAL:NO /LIBPATH:C:\Python27\libs /LIBPATH:C:\Python27\PCbuild /EXPORT:initexamp
le build\temp.win32-2.7\Release\example.obj /OUT:build\lib.win32-2.7\example.pyd
 /IMPLIB:build\temp.win32-2.7\Release\example.lib /MANIFESTFILE:build\temp.win32
-2.7\Release\example.pyd.manifest
   Creating library build\temp.win32-2.7\Release\example.lib and object build\te
mp.win32-2.7\Release\example.exp
C:\Program Files\Microsoft Visual Studio 8\VC\BIN\mt.exe -nologo -manifest build
\temp.win32-2.7\Release\example.pyd.manifest -outputresource:build\lib.win32-2.7
\example.pyd;2
running install_lib
copying build\lib.win32-2.7\example.pyd -> C:\Python27\Lib\site-packages
running install_egg_info
Removing C:\Python27\Lib\site-packages\example-1.0-py2.7.egg-info
Writing C:\Python27\Lib\site-packages\example-1.0-py2.7.egg-info

Now when I run C:\Python27\python.exe and try to import example I get the following...

ImportError: DLL load failed: The specified module could not be found.

Did I do something wrong? Is VS8 unsupported for creating Python 2.7 modules? What should I do?

Ultimately I need to build bindings for some Windows C library so that I can use Python to extend some proprietary program instead of C. I have to use VS8 for creating the C extension. So where does that leave me.

Advice please.

Thanks, ~Eric

If you must use VS8 and want Python 2.7, build your own version of it with VS8. Not sure what effect this might have on any other third-party extensions you might want to use unless you can rebuild them, too. — martineau
– martineau, Commented Nov 18, 2010 at 20:12

DaedalusFall · Accepted Answer · 2010-11-18 20:13:28Z

1

Generally speaking you have to build the python modules using the same version of VS as python was built with. You have several options:

Use Python2.6, which i think is VS8 (or an even earlier version, I'm sure there was a change between 2.5 and 2.6)
Use VS9. I assume you can't because the proprietary library you are using was built with VS8. Same problem as is happening with python really.
Create your bindings using ctypes. This can be hard and its very easy to crash your program.
Build Python2.7 from source using VS8. If you can't use Python2.6 for some reason then this is probably the best bet.

I'd recommend option 1 if it works.

edited Nov 18, 2010 at 20:13

answered Nov 18, 2010 at 19:31

DaedalusFall

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2 Comments

martineau Over a year ago

You can download the free version of VS 2008 from Microsoft here. I believe this is the same version that was used to compile Python 2.7. Not sure whether it could co-exist with an another version on the same system though...

eric.frederich Over a year ago

Thanks. I'll definitely give #1 a go. I already tried #4 and I could load the example pyd file that I created using Visual Studio. When I went to add another function to the module that called a library routine I became unable to import the package in pyhon and get the same import error I had before.

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