So far in this part of the book, we’ve concentrated on using Python’s OOP tool, the class. But OOP is also about design issues—that is, how to use classes to model useful objects. This chapter will touch on a few core OOP ideas and present some additional examples that are more realistic than many shown so far.

Along the way, we’ll code some common OOP design patterns in Python, such as inheritance, composition, delegation, and factories. We’ll also investigate some design-focused class concepts, such as pseudoprivate attributes, multiple inheritance, and bound methods.

One note up front: some of the design terms mentioned here require more explanation than I can provide in this book. If this material sparks your curiosity, I suggest exploring a text on OOP design or design patterns as a next step. As we’ll see, the good news is that Python makes many traditional design patterns trivial.