An introduction to object oriented programming, inheritance and method combination

Object oriented programming, introduced in the 1960's by Simula, has become an important programming framework for large software systems. Among the attractions of object oriented programming languages is the potential for software reuse through inheritance. Inheritance allows the programmer to define a new class of objects which inherit the procedures and state descriptions of an existing class. The programmer may then modify and extend the behavior and state of the base class. Because state information is static, subclassing state is straightforward: simply append new state information. However, behavior is dynamic; the problem of subclassing behavior is a bit more complicated, since it may not be correct to simply concatenate the behaviors of the superclass and the subclass and execute them sequentially. This issue is referred to as the method combination problem. In this paper, an overview of object oriented programming will be presented, with a description of the philosophy of object oriented programming. The different approaches to inheritance will be compared, followed by a discussion of the method combination problem. «r^SKS^r **̂ < D O D >' TM o * Avionics Laboratory Air Force Wright Aeronautical Laboratories Aeronautical Systems Division (AFSC) Wright-Patterson AFB, Ohio 45433-6543 Agency or No . Gov^menT' ^ ° f "* A d v a n c e d Inheritance and Method Combination 2