Question

Let’s say I’ve got some class that observe, and a class that is observed, I want to notify observers, but in a presented way.

class that is observed has a array of pointers to methods in class that observe.
So basically when I call notifyObservers in observed class, it would go through this array and simply call necessary functions in observers.
That solution was presented by my teacher, and I have hard time making it work, he sad that this solution doesn’t require holding pointer to obervers (like Observer design pattern) only pointers to methods. But how do I store pointers to a method that know who should call them

I tried something like this:

class A { 
public:
    void method();
} 
A a;   
void(A::*ptr)()=&a.method;
void (*ptr)()=&a.method; 

Which obviously didn’t work.
Is there even a way to make it work?

Answer 1

Try using bind:

std::function<void()> ptr = std::bind(&A::method, a);
ptr(); // calls a.method();

Note that as betabandido mentioned, this works only in C++11 as is or in older versions using boost.