Hi,
I'm currently embedding and extending Python using Boost.Python. I'm
trying to expose some c++ library (OIS) classes to my Python scripts.
This library mainly exposes abstract classes since the actual
implementation are derived classes specialized for each operating system.
So, i have to wrap those abstract classes. Then, eventually i will
convert some existing C++ object of this class to its Python equivalent.
Ideally, I would think that the HeldType is a pointer to the existing
C++ object. There is no pointer managment problem since the lifetime of
the object is greater than the execution time of the script.
There is probably something i don't understand in the design of
Boost.Python. At this point, my problem is that i need a to_python
conversion which requires the abscence of noncopyable attribute which
then implies to be able to build an instance of the object (which i
cannot provide since the class is abstract, and i don't have any
concrete derived class). I don't yet understand why holding a pointer in
the Python object requires the ability to build instances of the wrapped
class. The exact compile-time error i get is:
boost_1_44/boost/python/object/pointer_holder.hpp:194:14: error: cannot
allocate an object of abstract type 'OIS::Keyboard'
I'm using boost 1.44 (required by some other library) Python 3.2 and
MinGW/Msys. Module declaration:
BOOST_PYTHON_MODULE(OIS)
{
class_<Keyboard, Keyboard*>("Keyboard", no_init);
}
Python init:
try {
PyImport_AppendInittab("OIS", PyInit_OIS);
Py_InitializeEx(0);
object main(import("__main__"));
dict globals(main.attr("__dict__"));
globals["keyboard"] = ptr(keyboard);
}
catch (error_already_set&) {
PyErr_Print();
}
Did i choose the wrong desing ? Did i do something wrong ? What should i
do to solve this problem ?
Valentin Perrelle.
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