Undefined calling conventions in Python.h

[Jaco Naude]

On Jul 23, 1:10 pm, Fredrik Lundh <fred... at pythonware.com> wrote:
> Jaco Naude wrote:
> > What Visual C++ is doing is that it is looking for mangled names since
> > it does not know the DLL contains C functions. I've managed to work
> > around this by declaring the Python functions as follows before using
> > them in the C++ application side:
>
> > extern "C"
> > {
> >     void Py_Initialize(void);
> > }
>
> > This seems to work and the C++ application side is not looking for
> > mangled names any more. Is this the right way of doing it? It seems
> > unnecessary to have to declare each Python function you want to use
> > using the extern "C" way as shown above.
>
> Eh, are you saying that you're not including the Python.h file?  Because
> it does exactly that, for each and every public function in the C API.
>
> > It is probably more of a C++ question it turns out, but I would think
> > that someone in the Python group would use the Python DLL in C++. The
> > documentation also suggest that there is no extra work needed when
> > using C++ rather than C.
>
> Oh, but I do that all the time, without doing any extra work.  Both
> embedding Python in C++ programs and existing it with C++ extensions.
> And I'm definitely not alone.
>
> Here's an actual session, using the version of Visual Studio I happen to
> have on this machine (2003, I think) from the command line:
>
>  > more test.cc
>
> #include "Python.h"
> #include <iostream>
>
> main()
> {
>      Py_Initialize();
>      PyRun_SimpleString("print 'hello'\n");
>      Py_Finalize();
>
>      std::cout << "world\n";
>
> }
>
>  > cl cl -EHsc -MD -I \python25\include test.cc \python25\libs\python25.lib
> Microsoft (R) 32-bit C/C++ Optimizing Compiler Version 13.10.3077
> for 80x86
> Copyright (C) Microsoft Corporation 1984-2002. All rights reserved.
>
> ...
>
>  > test
> hello
> world
>
> If you cannot get the same console program to work in your compiler
> setup, something's wrong with your configuration.
>
> </F>

Ok that's probably good news, although it points out that there is
something wrong with my configuration since that does not work. I
would rather sort out the problem that having to defined each function
with a extern "C" command.

That said, let me double check something which might be causing
problems since you will be familiar with this. Which Python.h file do
you include when including the DLL in your programs? The one in the
source distribution of the one in the installation distribution? I've
been including the one in the installation distribution all along.
When I try to include the one in the source distribution it gets up to
the point where it looks for the following include:

#include "pyconfig.h"

This file is not in the same directory as the Python.h file in the
source distribution. Because of this I just used Python.h in the
installation distribution.

Thanks again,
Jaco