The Object-Oriented Thought Process, Fourth Edition

Why Encapsulation Is Fundamental to OO

Encapsulation is the fundamental concept of OO. Whenever the interface/implementation paradigm is covered, we are talking about encapsulation. The basic question is what in a class should be exposed and what should not be exposed. This encapsulation pertains equally to data and behavior. When talking about a class, the primary design decision revolves around encapsulating both the data and the behavior into a well-written class.

Stephen Gilbert and Bill McCarty define encapsulation as “the process of packaging your program, dividing each of its classes into two distinct parts: the interface and the implementation.” This is the message that has been presented over and over in this book.

But what does encapsulation ...