Python Object-Oriented Programming - Fourth Edition

11

Common Design Patterns

In the previous chapter, we were briefly introduced to design patterns, and covered the iterator pattern, a pattern so useful and common that it has been abstracted into the core of the programming language itself. In this chapter, we'll be reviewing other common patterns and how they are implemented in Python. As with iteration, Python often provides an alternative syntax to make working with such problems simpler. We will cover both the traditional design, and the Python version for these patterns.

In this chapter, we'll see:

• The Decorator pattern
• The Observer pattern
• The Strategy pattern
• The Command pattern
• The State pattern
• The Singleton pattern

This chapter's case study will emphasize how the distance calculation ...