Question

I am trying to store pointers to memberfunctions of different Classes in C++. What are the possibilities in C++?

I would like to do this:

class A {
    T0 f(T1,T2);
};

class B {
    T0 g(T1,T2);
    T0 h(T1,T2);  //interfaces cant be used since the number of functions per class differs.
};

typedef WHATTOPUTHERE type;

type x;
x = A::f;
x = B::h;

Update: Another Problem is that the code should be continueable like this:

B myB;
myB::x(a,b); //not sure about the syntax, should result in myB::h(a,b) being called

This means that I can not bind at the time I store the pointer, since the instance does not exist (yet).

Answer 1

Function objects to encapsulate your function pointers should work.

boost::function is one option, maybe something like this:

class SomeObj
{
public:
   void SetInt(int i);
};

SomeObj myObject;
std::vector<boost::function> memberFuncs;
// in the template arg to boost::bind specify the function type
// _1 here denotes late binding so you can pass whatever value you want when invoked
// you could simply bind a parameter as a variable or literal instead
memberFuncs.push_back(boost::bind<void(int)>(&SomeObj::SetInt, &myObject, _1));
memberFuncs[0](42); // myObject->SetInt(42);

Untested/uncompiled code disclaimer this is just for a general idea.