Executable UML: A Foundation for Model-Driven Architecture

6.5. Generalization and Specialization

All of the instances of a class must share common characteristics and common behavior. But we often face things that are somewhat common yet somewhat different.

6.5.1. The Concept of Generalization and Specialization

In Section 5.5: Checking Classes and Attributes, we presented a Product as an example of a uniformity problem. The online store sells more than just books; it also sells videotapes, CDs, DVDs, and computer software. All these products have a sale price and are identified by a universal product code (UPC). Books have an ISBN number; CDs, videotapes, and DVDs have a running time; computer software titles have version numbers. We noted a uniformity problem that made a single Product class undesirable ...