How do I limit protected inheritance of members to only one or a few generation(s)?

Question

My class Dad provides some protected methods, that its children will need, even if it doesn't actually know yet who these children will be.

class Dad
{
protected:
    void method()
    {
        // some amazing stuff (I swear)
    };
};

The actual inheriting class Child: public Dad, in the current implementation of my program, has decided to be derived itself into several classes class GrandKid1: Child, class GrandKid2: Child etc.

But, for the sake of safety and organisation, Child prefers the grandkids not to be able to call the method() by themselves. How do I prevent them from doing this?

Obviously, the following naive code yields a linker error:

class Child: public Dad
{
private:
    void method();
};

How do I make Child stop the propagation of the protected member method() to its own derived classes?

Answer 1

You can use using directive to put member into another section.

class Dad
{
protected:
    void Method() { std::cout << "Dad"; }
};

class Child : public Dad
{
private:
    using Dad::Method;
};

class GrandChild : public Child
{
public:
    void f1() { Method(); } // Generates compilation error
};