Question

I don’t understand why the compiler doesn’t like this, here is and example of the problem:

class A
{
public:
    virtual void Expand() { }
    virtual void Expand(bool flag) { }
};

class B : public A
{
public:
    virtual void Expand() {
        A::Expand(true);
        Expand(true);
    }
};

When I try to compile this the A::Expand(true); compiles fine, but the non scoped Expand(true); gets this compiler error:

‘B::Expand’ : function does not take 1 arguments

Answer 1

That’s because besides overriding the base Expand(), you’re also hiding the base Expand(bool).

When you introduce a member function in a derived class with the same name as a method from the base class, all base class methods with that name are hidden in the derived class.

You can fix this by either qualifying (as you have) or with the using directive:

class B : public A
{
public:
    using A::Expand;
    virtual void Expand() {
        A::Expand(true);
        Expand(true);
    }
};