Access specifier while overriding methods

Question

Assume you have a class that defines virtual methods with the access specifier public. Can you change the access specifier on your overriden methods? I am assuming no. Looking for an explanation.

Answer 1

The answer is: sort of. You can only change the access of members the derived class has access to. The type of inheritance has no effect - this only controls the default access for inherited members (to a point, following other rules).

So, you can make a base class's protected members public or private; or a base's public members protected or private. You cannot, however, make a base's private members public or protected.

Example:

class Foo
{
protected:
        void protected_member();

private:
        void private_member();

public:
        void public_member();
};

class Bar : private Foo
{
public:
        using Foo::protected_member;
        using Foo::private_member;
        using Foo::public_member;
};

int main(int, const char**)
{
        Bar bar;

        return 0;
}

The above code elicits the following error on g++ 4.1.2:

main.C:7: error: 'void Foo::private_member()' is private

main.C:14: error: within this context

Additionally, overriding has nothing to do with changing the access of a method. You can override a virtual private method, you just cannot call it from a derived class.