[C++-sig] converting objects to python..

[Dominique Devriese]

Hi, 

I have been looking at this for some time, and I can't seem to find
it.  Maybe someone here can help ?  

(I'm using Boost.python to export the api of an app that i want to
embed python in.. ( http://edu.kde.org/kig in case someone is
interested ) )

I'm trying to call a python function from C++ code with some
arguments.  The arguments are of type "const ObjectImp*", where
ObjectImp is the abstract base class of a whole lot of other types.
All of them are properly wrapped, and I have tested the wrapping in
different situations, and it works.  The problem is that I can't seem
to find how to convert a "const ObjectImp*" to a PyObject.  I tried:

const ObjectImp* the_object_imp_pointer;
object o( the_object_imp_pointer );
use( o.ptr() );
object o2( *the_object_imp_pointer );
use( o2.ptr() );

( and a whole lot of other things that would only make me look stupid
here, so i'll omit those ;) )

In both cases, the object constructor throws an error_already_set
exception, and from the debugging in boost.python internals I've done,
it appears that this happens because the lib doesn't have a converter
registered for the types. 

I thought about trying to write a converter myself, but then I thought
that this would be stupid, since I wouldn't know how to do this,
unless i found out how boost.python PyObject's work, and it seemed
more intelligent to just ask here first ;)

At one point, I also thought that the problem would be that i should
first downcast the pointers to their "real" type, and try to convert
that, but then I thought that would not be the case, since you're
using typeid() in the conversion stuff, and that only takes into
account the "real" type, not the formal type, so downcasting is not
necessary..

Anyway, I'm kinda stuck on this..  Could you give me some pointers on
where to look ?

thanks
domi

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