C++ - is it possible to extract class and argument types from a member function type in a template?

Question

I would like to wrap member functions that conform to the type \'void (ClassType::Function)(ArgType)\' with a templated class. Later, I want to pass an instance of ClassType to

Answer 1

In C++11 you might use lambdas, like:

template 
std::function wrapper(void (X::*mfp)(ARG))
{
    return [=](X *x, ARG arg) {
       (x->*mfp)(arg);
    };
}

With VisualC++ (at least as recent as VS2013), use capture by value [=] when capturing member function pointers (or experience crashes).

Playground:

#include 
#include 

struct A {
    virtual void a(int i) { std::cout << "A: " << i << std::endl; }
};

struct B {
    virtual void b(int i) { std::cout << "B: " << i << std::endl; }
};

template 
std::function wrapper(void (X::*mfp)(ARG)) {
    return [=](X *x, ARG arg) { (x->*mfp)(arg); };
}

int main()
{
    auto g = wrapper(&B::b);
    B b;
    g(&b, 3);
    auto h = wrapper(&A::a);
    A a;
    h(&a, 4);
    return 0;
}