Object-Oriented Analysis and Design

Let’s summarize the rules of thumb for good object-oriented design. The programmer is concerned with writing class definitions, while at run time, it is appropriate to talk of objects and their interactions: 1. Each class should be self-contained, providing a complete service of some kind. 2. Each should have a simple and small interface couched in the language of the appli-cation domain. If this is so, users of the class are able to ignore the details of its internal structure and implementation and concentrate on the interface. We call this abstraction. See Fig. 3. 3. Classes should hide their data, we call this encapsulation, only providing a small number of controlled methods or functions in the interface for accessing that data. These factors taken together enable separation of interface from implementa-tion. The actual designs of the algorithms employed inside the classes can be changed as better, more efficient algorithms are found. After a design is complete, changes in a class implementation must not affect its interface. The effect on current and future users is then only in terms of efficiency: their applications need not be recoded to tak