Object-Oriented Programming Defined

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Object-oriented programming is several things: First, it is a way of thinking about how abstractions called objects interact. Object-oriented thinking is different from procedural thinking. Object-oriented thinking empowers you to tame conceptual complexity. The analysis of objects and their interaction within a problem domain is referred to as Object-Oriented Analysis and Design (OOA&D).

Second, object oriented programming is a way of executing in code the design derived from applying OOA&D. Programming languages like C++, Java, SmallTalk, etc., provide features that support object-oriented programming. However, simply programming in an object-oriented language does not constitute object-oriented programming. For instance, merely converting an existing C program to C++ does not imply the converted code is now magically object-oriented.

Object-oriented programming is the implementation and application of polymorphic classes to create a software application. In C++ polymorphic classes are created with a combination of language features. Abstract base classes, virtual or pure virtual functions, public inheritance, derived classes, and base class pointers or references pointing to derived class objects all combine to enable the execution of an object-oriented design. Essentially, to write object-oriented programs in C++ requires an understanding of almost every language feature.

An object-oriented program is designed to utilize dynamic polymorphism. The application architecture is described and implemented in terms of object interfaces. A well-designed application architecture is stable and extensible.

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