Calling a C++ function pointer on a specific object instance

Question

I have a function pointer defined by:

typedef void (*EventFunction)(int nEvent);

Is there a way to handle that function with a specific instance of a C++ object?

class A
{
private:
    EventFunction handler;

public:
    void SetEvent(EventFunction func) { handler = func; }

    void EventOne() { handler(1); }
};

class B
{
private:
    A a;
public:
    B() { a.SetEvent(EventFromA); }  // What do I do here?

    void EventFromA(int nEvent) { // do stuff }
};

Edit: Orion pointed out the options that Boost offers such as:

boost::function<int (int)> f;
X x;
f = std::bind1st(
      std::mem_fun(&X::foo), &x);
f(5); // Call x.foo(5)

Unfortunately Boost is not an option for me. Is there some sort of "currying" function that can be written in C++ that will do this kind of wrapping of a pointer to a member function in to a normal function pointer?

Answer 1

You can use function pointers to index into the vtable of a given object instance. This is called a member function pointer. Your syntax would need to change to use the ".*" and the "&::" operators:

class A;
class B;
typedef void (B::*EventFunction)(int nEvent)

and then:

class A
{
private:
    EventFunction handler;

public:
    void SetEvent(EventFunction func) { handler = func; }

    void EventOne(B* delegate) { ((*delegate).*handler)(1); } // note: ".*"
};

class B
{
private:
    A a;
public:
    B() { a.SetEvent(&B::EventFromA); } // note: "&::"

    void EventFromA(int nEvent) { /* do stuff */ }
};