Chapter 8 mentioned that applications development is about algorithms and data. The two design patterns in this chapter model the ways applications can deploy software factories to create objects during run time.
The Factory Method Design Pattern provides a model for creating a group of related objects. Our example application shows how the design pattern allows a school athletic department to delegate responsibilities to the varsity sports and intramural sports organizations. The Abstract Factory Design Pattern goes further and provides a model for creating families of objects, preventing mixing objects from different families. We’ll expand the example application to ensure that the varsity and intramural sports organizations keep their responsibilities apart.
In this chapter, we’ll develop another example application incrementally. We’ll adapt the appropriate patterns one at a time to model solutions to the architecture design problems as we encounter them.
NOTE
Be sure to read the introduction to part 4 for important information about design patterns in general and to learn how this and subsequent chapters teach each pattern.