Your approach is exactly what we don't want, since it makes it an object-based based solution rather than instance-based. We are using a functor (therefor the oprerator()) so that the solution remains instance-based.

Is your application threaded? If so couldn't you use thread_specific_ptr for emulating a instance-based functor? class A; class B; class C { public: C() { instance().push_back(this); } ~C() { instance().pop_back(); } int operator()(A* a, B* b) { // Do your stuff. } static int wrapper(A* a, B* b) { return instance().back()->operator()(a, b); } private: C(const C& rhs); C& operator=(const C& rhs); static this_vector& instance() { this_vector* t = ptr.get(); if (!t) { t = new this_vector(); ptr.reset(t); } return *t; } typedef std::vector this_vector; static boost::thread_specific_ptr ptr; }; typedef int (*foobar)(A*,B*); void do_something(foobar cb); C obj; do_something(C::wrapper); Regards, Anders