Re: Access to C++ dlls from Python

Please reply to the mailing-list, not me personally.

Am 29.10.2010 um 16:16 schrieb bifferos:

>
> I thought the wrappers were more for the case where you had the source
> for the wrapped functions.  I've still got to find an load the DLL,  
> then
> pass object pointers into my wrapper code.   Also, the wrapper
> requires that I have the relevant vc2003 license (my dll was compiled
> with that).  Actually, more to the point, I'm not sure you can even  
> buy
> the vs2003 compiler, although you can get the later ones, and the ABI
> may well be the same.
>
> For information, I have the headers for the classes, the DLL  
> consists of
> a 'factory' function which returns a void ptr to an object instance.
> The interface I'm using is pure virtual, so it becomes a little  
> simpler
> in the memory layout.
>
> I'd very much like to have any references to these 'attempts' you're
> speaking of.  I'd take non-working code over nothing at this stage.

None of this is relevant AFAIK. Wrapper-generators also only need  
headers and of course the library itself. Then the extension will be a  
DLL of it's own, loading/linking to the original C++-DLL.

The compiler-question is potentially an issue if there is a mismatch  
between the MSVCRT-variants Python and your DLL use, but that's a  
problem under all circumstances.

The discussions have taken place on this list, please google them. I  
can't comment on the state of affairs there, but in all honesty:  
creating a patched + proprietary version of ctypes is *way* more  
effort that to create C++ extension.

ctypes-C++ support would only be useful if it would work the same way  
as ctypes does - seamless, without the need to invoke a compiler. It  
doesn't, and it seems to be a problem that's pretty hard.

If you don't want to go down the C++-wrapper route, you might consider  
wrtiting a simple C-API-wrapper that can be loaded using ctypes. That  
however depends how high the trade-off between wrapping by hand and  
generating is. The richer the C++-interface, the more you should check  
out SIP.

Diez

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