Lesson 15 - Polymorphism in C++

In the previous lesson, A mage for the C++ arena, we created a mage. He can fight, but he's not in the arena yet. We haven't added it to the arena because it can only handle warriors so far. So in today's tutorial, we have to tell C++ that Mage is really a warrior and can be treated like one.

Polymorphism

Don't be scared of the obscure name of this technique, it's actually very simple. Polymorphism allows us to use a unified interface to work with objects of different types. Imagine that we have, for example, many objects representing geometric shapes (circles, squares, triangles, and so on). It'd certainly be helpful if we could communicate with them in some unified way even though they're different. We can create a GeometricShape class containing a color field and a render() method. All the geometric shapes would then inherit the interface from this class. Now you may be thinking, "But the circle and square object would render differently!." Well, polymorphism allows us to override the render() method in every subclass so it will do what we want. The interface will be unified and we won't have to think about which method to call to render different objects.

Polymorphism is often explained using animals. All having a speak() method in their interface, but each animal performs it differently:

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