Beginning C# 2008 Objects: From Concept to Code

7.3. Abstract Classes

You learned in Chapter 5 how useful it can be to consolidate shared features—fields and behaviors—of two or more classes into a common base class, a process known as generalization. We did this when we created the Person class as a generalization of Student and Professor and then moved the declarations of all their common fields methods and properties into this base class. By doing so, the Student- and Professor-derived classes both became simpler, and we eliminated a lot of redundancy that would otherwise have made maintenance of the SRS much more cumbersome.

The preceding example involved a situation in which the need for generalization arose after the fact; now let's look at this problem from another perspective. Suppose ...