[Boost-users] [Boost.Python] Using Inheritance and Virtual Functions in a Python Binding

20 Oct 2009

      Hi,

I can't seem to get inheritance and virtual functions to work together 
in a simple python binding:

#include <boost/python.hpp>
using namespace boost::python;

struct Base
{
	virtual ~Base() { }
	void nonVirtualFunc() { }
	virtual void virtualFunc() { }
};

struct Derived : public Base
{
	~Derived() { }
	void virtualFunc() { }
};

struct BaseWrap: public Base, public wrapper<Base>
{
	void virtualFunc()
	{
		if (override virtualFunc = this->get_override("virtualFunc"))
			virtualFunc();
		else
			Base::virtualFunc();
	}
	void default_virtualFunc() { this->Base::virtualFunc(); }
};

BOOST_PYTHON_MODULE(test)
{		
	class_<Base, boost::noncopyable>("__Base")
		.def("nonVirtualFunc", &Base::nonVirtualFunc)
	;

	class_<BaseWrap, boost::noncopyable>("Base")
		.def("virtualFunc", &Base::virtualFunc, &BaseWrap::default_virtualFunc)
	;

	class_<Derived, bases<Base> >("Derived")
		.def("virtualFunc", &Derived::virtualFunc)
	;
}

Now in my python interpreter:
...
...
...
import test
dir(test.__Base)
[<built-ins>, 'nonVirtualFunc']
dir(test.Base)
[<built-ins>, 'virtualFunc']
dir(test.Derived)
[<built-ins>, 'virtualFunc']
Without using BaseWrap to do the virtual functions:
...
...
...
dir(test.Derived)
[<built-ins>, 'nonVirtualFunc', 'virtualFunc']
It seems that by using the boost python wrapper, I now lose any 
inherited functions, and the nonVirtualFunc does not get defined in the 
subclasses. I may be going about this in the wrong way, but is there a 
way of using inheritance and virtual functions together?

Thanks,
Dan

[Boost-users] [Boost.Python] Using Inheritance *and* Virtual Functions in a Python Binding

Dan Bailey

[Boost-users] [Boost.Python] Using Inheritance and Virtual Functions in a Python Binding