C API function callbacks into C++ member function code

Question

So, I\'m using the FMOD api and it really is a C api.

Not that that\'s bad or anything. Its just it doesn\'t interface well with C++ code.

For example, usin

Answer 1

There is a non-portable, and pretty hackish solution that has the advantage of at least being thread-safe, which the "trampoline" methods are not.

You can generate the actual function machine code on the fly. The basic idea is that you have a template for your call-back function that takes an object pointer and a member-function pointer and gives you a block of heap memory that you can pass to the library as a C call-back function, that will, when called, turn around and call the member function on that object.

It's messy, and you'll have to provide an implementation for any new platform (any time the calling convention changes), but it works, is thread-safe. (Of course you'll also have to watch out for DEP). The other thread-safe solution is to resort to thread-local storage (assuming that you know the call-back will happen on the same thread as the call you made).

See http://www.codeproject.com/KB/cpp/GenericThunks.aspx for an example of how you could go about generating thunks.