Pass Member Function Pointers to parent class

Question

I'm working on a Pacman game in C++, but have run into a problem with member function pointers. I have 2 classes, pacman and ghost , that both inherit from Mouvement . In the subclasses, I need to pass a function to a function in Mouvement . However, I can't simply have static functions as then I would need static variables, which would not work.

I have tried passing &this->movingUp which throws the error 'Cannot create a non-constant pointer to member function'

I have tried passing &<ghost or pacman>::movingUp which throws the error "Cannot initialize a parameter of type 'void ( )(int)' with an rvalue of type 'void (:: )(int)' "

Here's what's relevent: (I cut out most of it, so that you only see what's necessary for this problem)

class cMouvement {
protected:

    int curDirection = -3; // Variables that are used in the 'movingUp, etc' functions.
    int newDirection = -3; // And therefore can't be static


public:

void checkIntersection(void (*function)(int), bool shouldDebug){

    // Whole bunch of 'If's that call the passed function with different arguments

}

And then class pacman and ghost , which are very similar at this point.

class pacman : public cMouvement {

    void movingUp(int type){
        // Blah blah blah
    }

    // movingDown, movingLeft, movingRight... (Removed for the reader's sake)



public:
    /*Constructor function*/

    void move(bool shouldDebug){
        if (curDirection == 0)     {checkIntersection(&movingUp, false);}
        else if (curDirection == 1)     {checkIntersection(&movingRight, false);}
        else if (curDirection == 2)     {checkIntersection(&movingDown, false);}
        else if (curDirection == 3)     {checkIntersection(&movingLeft, false);}
    }

};

Answer 1

为什么不在cMouvement创建虚函数，让checkIntersection调用该虚函数

Answer 2

What you want is to supply the signature of a member function, instead of a regular function.

void checkIntersection(void (ghost::*)(int), bool shouldDebug){

See Passing a member function as an argument in C++

If you really need to supply functions from ghost and pacman you need to rethink your strategy. Maybe use virtual functions instead.