gistfile1.hpp

template <typename T> class Delegate;
template <typaname T> class DelegateFunction;

// Specialization for 2-argument callbacks:
template <typename C, typename R, typename A1, typename A2>
class DelegateMemberFunction : public DelegateFunction<R, A1, A2> {
private:
    C* m_Instance;
    R (*m_Function)(A1, A2);
public:
    // ... constructor
    R invoke(A1 a1, A2 a2) { return (m_Instance->(*m_Function))(a1, a2); }
};

template <typename R, typename A1, typename A2>
class Delegate<R(A1, A2)> {
private:
    DelegateFunction<R(A1, A2)>* m_Function;
public:
   // Member function constructor
   template <typename C>
   Delegate(C* instance, R(C::*function)(A1, A2)) {
       m_Function = new DelegateMemberFunction<C, R, A1, A2>(instance, function);
   }
   
   // Free function constructor
   Delegate(R(*function)(A1, A2)) {
       m_Function = new DelegateFreeFunction(R, A1, A2>(function);
   }

   R invoke(A1 a1, A2 a2) { return m_Function->invoke(a1, a2); }
};

template <C, R, A1, A2>
Delegate<R, A1, A2> CreateDelegate(C* instance, R(C::*function)(A1, A2)) {
    return Delegate<R, A1, A2>(instance, function);
}