C++ functor templates

Given the following class, which simply maps an internal functor f to a function to be run later:

class A {
private:
   int (A::*f)(int);
   int foo(int x) { return x; }
   int bar(int x) { return x*2; }
public:
   explicit A(bool foo=true) { f = foo ? &A::foo : &A::bar; }
   int run(int x) { return (this->*f)(x); }
};

Now say I have another class, B:

class B {
public:
   int foo(int) { return x*x; }
};

And function foo:

int foo(int x) { return 0; }

I know it is not possible to have A assign and run B::foo or foo as their prototypes differ: int (A::*)(int) vs int (B::*)(int) vs int (*)(int).

What I am asking, is their any way to te开发者_高级运维mplatize A::f such that it could take any of them?

Normally, you use a std::/boost::/std::tr1 ::function<int(int)> for this kind of job. It can take any function object (including pointer) with the correct signature. You can create function objects that call member functions using bind, available in the same package.

I am not exactly sure what you are trying to achieve, but you may want to look into:

• Boost.Function - can wrap any kind of callable
• Boost.Bind - can be used to bind a member function to an instance