Public and Private View

In C++ and Java, Parnas's principles find direct correspondance in a pair of ideas called the public and private views of a class.
The public view consists of those features, both data and behavior, that other components can see and use.
The private view consists of those features, data and behavior, that are used only within the conpoment, and cannot be seen by others outside.

Eventually, when we introduce inheritance, we will see that there are really three views of a component, since a subclass has neither the public nor the private view of its parent.

[audio] 29 [real] 29 Text to accompany slide 29, in Chapter 2 of An Introduction to Object-Oriented Programming