Software Engineering and Computer Games

3.4. The essential Pop classes

To help organize this discussion, let’s start with a UML class diagram of some of the main classes involved in the Pop Framework. We’ll give a more detailed explanation of how to ‘read’ UML class diagrams in Section 3.5. For this initial diagram, we use three conventions.

First, we represent a class by the class name inside a rectangle. Second, we represent the class relationship of composition by a line with a diamond at one end. The composition relationship means that a class object of the type at the diamond end owns or has as members class objects of the type at the other end. You can think of the diamond as a ‘socket’ where we ‘plug in’ one or more instances of the class at the other end of the composition ...