Name Hiding

Name hiding is a feature of C++. Quoting from C++ FAQs by Marshall P. Cline and Greg A. Lomow :

What is the hiding rule? A member of a derived class hides any member of a base class that has the same name as the derived class member.

Here's an example of the problem:

 class Base
    {
    public:
    virtual void foo( int const & x ) { m_foo = x; }
    virtual int foo( void ) const { return m_foo; }

    private:
    int     m_foo;
    };

 class Derived : public Base
    {
    public:
    virtual void foo( int const & x ) { Base::foo( x ); DoFooChanged?(); }
    void DoFooChanged?( void ) {}
    };

  Derived d;
  cout << d.foo();  // COMPILER ERROR int foo( void ) is hidden.

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In post-standard C++ one would fix the problem with a using-declaration like:

 class Derived : public Base
    {
    public:
    using Base::foo;
    // ... as before
    };

This brings the foo of the base scope into the derived scope. In practice this is only a slight inconvenience in situations like this. -- DaveHarris

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CategoryCpp