Pointer to a class and function - problem

Question

Firstly I'll show you few classes.

class A {
public:
    B * something;

    void callSomething(void) {
        something->call();
    }
};

class B {
public:
    A * activeParent;

    B(A * parent) {
        activeParent = parent;
    }

    void call(void) {
        activeParent->something = new C;
    }
};

class C : public B {
public:
    A * activeParent;

    C(A * parent) {
        activeParent = parent;
    }

    void call(void) {
        // do something
    }
};


A * object;
object = new A;
object->something = new B;
object->callSomething();

My app needs such a structure. When I do callSomething(), it calls B's call() but when B's call() changes the "something" to C, C's call() is triggered and I want to avoid that. How should I do?

Answer 1

Aside from the design decisions (e.g., cyclical dependencies)...

The only reason A's callSomething() method would call C's call() method from a pointer to B is if the call() method is virtual. To avoid calling C's call() method, here are a couple of options:

• Don't make the call() method virtual
• Rename one of B or C's call() method (preferred over the first option)
• Call B's call() method explicitly

To call B's call() method explicitly:

void callSomething(void) {
    something->B::call();
}