C++: How do I pass a pointer to a member function of another class?

Question

How would the signature for function Foo() fo class classA have to look when I want to pass a pointer to a function that is a member of classB? Function update() is called on an isntance of classB and gets passed an object of classA. Inside update() the function Foo() of classA shall be passed a pointer to a callback function. That function is a member of classB. I can't make anything static here. Is there a way to do this, maybe with boost::function ?

Code:

class classA
{
 public:
  voif Foo(/*a pointer to a memberfunction of ClassB*/)
};

class classB
{
 classB(){nVal = 0;}
 int nVal;
 public:
 void increment(int n){nVal += n;}
 void update(classA objA)
 {
  objA.Foo(increment)
 }
};

Answer 1

You can use boost::bind with boost::function.

class classA
{
public:
   void Foo(const boost::function<void(int)>& function)
   {
   }
};

class classB
{
public:
   //
   void update(classA objA)
   {
       objA.Foo(boost::bind(&classB::increment, this, _1));
   }
};