Re: [Boost-users] Define a callback member function inside the object instance

On Fri, Aug 28, 2009 at 4:16 AM, Daniele Barzotti<daniele.barzotti@eurocomtel.com> wrote:

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Hi,

I would ask you a suggestion. In according with the FAQ (http://www.parashift.com/c++-faq-lite/pointers-to-members.html#faq-33.2) is better to not set a non-static member function like a callback.

But If I need to pass that callback inside my object, I'm pretty sure that the object itself exist!

So if I have a callback signature like this:

int my_callback(void *outputBuffer,                void *inputBuffer,                unsigned int nFrames,                double streamTime,                int status,                void *userData )

And I want to bind it to a member function:

int MyObject::my_callback(....)

Now, inside the object I have something like:

MyObject::OneMethod() {  p_AnotherObject->SetCallBack( ???? ); }

How can I pass my MyObject::my_callback to SetCallBack using boost::function and/or boost::bind?

If the callback is a real function pointer and not boost::function, you cannot. Bind creates a functor, which cannot be placed in a C style function pointer, you need a C++ style function pointer (std/boost::function). Your best bet would be to stick the instance in the userData and call back to your instance.