Microsoft® Visual C#® .NET 2003 Kick Start

Working with Polymorphism

Using virtual methods and the override keyword, you can implement polymorphism, the capability to determine at runtime which type of object is stored in a variable and to call that object's methods correctly. For example, if you derived Menu from a base class named Window and each of these classes had a different virtual version of the Open method, you could put off until runtime which type of object, Window or Menu, to place in a Window variable. If you put a Window object into a Window variable and called its Open method, Window.Open would be called, but if you placed a Menu object into a Window variable (which is legal since Menu is derived from Window) and called its Open method, Menu.Open would be called.

In other ...