Re: [boost] how to get a *real* copy of a boost-python object that supports virtual function

From: Phil Austin (paustin_at_[hidden])
Date: 2001-11-23 19:55:07

(I'm posting to both boost and boost-users, but I'm assuming we're
supposed to move this kind of discussion to Boost-Users_at_[hidden]?)

dkottowk_at_[hidden] writes:

[snip]

 > my question is, how do i get a copy of PyGenome_Callback, 
 > which also is a copy of the python-side of the object ?

I'd also be interested in a pointer to an elegant way to do this,
as well as an example of a from_python function that converts PyObject* to
PyGenome_Callback.

Brute force does work for me -- i.e. if you need the derived class and
can't construct the object in Python code, you can call the
derived constructor from the C++ side like this:

    PyObject* theMod=PyImport_ImportModule("mymodule");
    PyObject* theDict=PyModule_GetDict(theMod);
    py::ref theRef(theDict);
    py::dictionary modDict(theRef);
    py::ref constructor=bDict.get_item(py::string("theObject").reference());
    PyObject* theInstance=PyObject_CallObject(constructor.get(),0);

This was ugly enough so that I added a python wrapper around my
extension to construct the derived objects I needed in Python and
pass them back to C++.

Phil