C++ understanding cocos2d-x use of function pointers

Question

I am experimenting around with extending cocos2d-x CCMenuItem components and came across something I have not seen before in C++. It would be helpful if someone would elabor

Answer 1

void (CCObject::*)(CCObject*) is a method pointer type (one type of pointer to member), not an ordinary function pointer. It's a pointer that can point to an instance method of the CCObject class that takes a parameter of CCObject* type. The type of class it's a method of is part of the pointer type (denoted by the CCObject::), similar to the parameters (because underneath, a pointer to the "current object" is a hidden parameter to all instance methods, this).

The typedef simply defines SEL_MenuHandler to be a synonym for that method pointer type.

To use a method pointer, you need to provide both an instance to act as this, as well as the arguments, using a syntax like this:

CCObject* object;
CCObject* anotherObject;
SEL_MenuHandler methodPointer;
(object->*methodPointer)(anotherObject);
// or equivalently: ((*object).*methodPointer)(anotherObject);

How would C++ handle this if the function was not passed by pointer. Is a function treated like an object with a copy constructor?

In C/C++, it is not possible to have an expression of "function type" or "method type". Any time you try to get something of "function type", it is automatically converted to a "pointer to function" type.