extending python with a C-written dll

Jean-Baptiste PERIN jb_perin at yahoo.fr
Tue Dec 21 10:59:50 CET 2004


John Machin a écrit :

> Jean-Baptiste PERIN wrote:
> 
>>Hi,
>>
>>I'm trying to make a windows dll reachable from a python script ..
> 
> and
> 
>>I'm encountering troubles during link step ..
>>
>>I use "lcc" to compile and link
>>I use python 2.3 under win XP
> 
> [snip]
> 
>>Here are the errors :
>>---------------------
>>Error c:\...\plugins\hello.c 14 undefined reference to
> 
> __imp__Py_BuildValue
> 
>>Error c:\...\plugins\hello.c 46 undefined reference to
> 
> __imp__Py_InitModule4
> [snip]
> 
>>     return Py_BuildValue("i", 1);
> 
> [snip]
> 
>>void __declspec(dllexport) inithello()
>>{
>>     (void)Py_InitModule3("hello", helloMethods, MHello__doc__);
>>Can anyone help me?
> 
> 
> Yes. Option 1: *Maybe* you can help yourself. Have you not noticed from
> the above that the compiler is magically prepending "__imp__" to the
> names of external functions? However the .lib that comes with Python
> won't have that "__imp__". You would have to bridge that gap, somehow.
> Have you searched the lcc documentation? Are you prepared for the next
> several problems that may arise?

Indeed, it's something I can't understand (the __imp__ stuff)..
Nothing appear about that in the
I have posted a question on lcc forum .. the author of lcc answered

"This happens because somewhere you are declaring the functions
Py_BuildValue
and
Py_InitModule

as __declspec(dllimport) "

He's right !!
He adviced me to change that ..
I don't want to make changes to python code .. so .. bye bye lcc

long life to gcc

> By the way, lcc also *appears* to change "...Module3" to "...Module4"
> :-)

this one is explainable to me .. it is due to the fact that both 
function are equivalent

in mod support.h:

#define Py_InitModule3(name, methods, doc) \
	Py_InitModule4(name, methods, doc, (PyObject *)NULL, \
		       PYTHON_API_VERSION)


> Option 2: You have been helped already. There are two free compilers
> which work quite well for developing extensions in C for win32
> platforms; start reading here:
> 
> http://docs.python.org/inst/tweak-flags.html#SECTION000620000000000000000
> 

I'm currently attracted by the cygwin solution .. that I find very sexy !!
If I fail .. I will explore the MingW ..

Thank you very much for helping me ..



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