Using function pointers for C++ class member function callbacks

func_pointer.cpp

#include <cstdlib>
#include <iostream>

class A {
    public:
    int callback(float variable) {
        int result =6;
        std::cout << "Callback invoked with result: " << result + variable << std::endl;
        return result;
    }
    
};

typedef int (A::*CallbackType)(float); // means CallbackType is a type definition for any function in A with a float argument 
//and a return type of int

void DoWorkObject(CallbackType callback) {
    //Class instance to invoke it through
    A objectInstance;

    //Invocation
    int result = (objectInstance.*callback)(1.0f);
}

//This method performs work using an object pointer

void DoWorkPointer(CallbackType callback) {
    //Class pointer to invoke it through
    A * pointerInstance;

    //Invocation
    int result = (pointerInstance->*callback)(1.0f);
}

int main() {

    DoWorkObject(&A::callback);
    DoWorkPointer(&A::callback);
    // These functions are regiistered with callback functions.
    // When they are done they can notify by calling these callbacks
    // i.e. callback is similar to OnMouseClieck and DoWorkObject/DoWorkPointer are smiliar to actual events

}