[C++-sig] Not using virtual method

[bob bob]

Hello, I'm having difficulties concerning using callbacks that have been extended in python. I'm using the windows video API DirectShow to play video to a screen through a transform method. The problem occurs when the Transform method is called from an object extended in python as a callback, not when called explicitly. How do I represent this functionality and prevent the python interpreter from crashing? I would like to try creating a thin wrapper to allow play to allow threads,

how can you do this?

 

Many Thanks,

Richard

 

// Cut down version of the C++ code

 

class Callback

{

            virtual void Transform() = 0;

}

 

class Player

{

            Player(Callback *);

            void Play();        // Play the video to the screen, returns allowing video to continue play

}

 

class Callback_Wrap : public Callback

{

            Callback_Wrap(PyObject *obj) : self(obj) {}

            virtual Transform() {call_method<void>(self, "Transform");}

            PyObject *self;

}

 

BOOST_PYTHON_MODULE(MyVideo)

{

            class_<Callback, boost::noncopyable, boost::shared_ptr<Callback_Wrap> >("Callback")

                        .def("Transform", &Callback::Transform)

                        ;

 

            class_<Player>("Player", init<Calback *>())

                        .def("Play", &Player::Play)

                        ;

}

 

 

# Example python use

 

from MyVideo import *

 

class My_Callback(Callback):

            def Transform(self):

                        print "Hello, My_Callback here!"

 

a = My_Callback()

b = Player(a)

a.Play()
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