The Smalltalk-like collection classes inherit from the abstract base class RWCollection, which in turn inherits from the abstract base class RWCollectable, described in Designing an RWCollectable Class, Creating an RWCollectable Object, Complete Listing for Class Bus, and Tables of the Smalltalk-like Classes. (Thus do we produce collections of collections, but that is another story.)

An abstract base class is a class intended to be inherited by some other class, not used as itself per se. If you think of it as a kind of virtual class, you can easily project the meaning of virtual functions. These virtual functions provide a blueprint of functionality for the derived class. As an abstract base class, RWCollection provides a blueprint for collection classes by declaring various virtual functions, such as insert(), remove(), entries(), and so on.

This section describes the virtual functions inherited by the Smalltalk-like collections. Any of these collections can be expected to understand them.