Chapter 10
The Iterator Pattern
We’ve discussed how many of Python’s built-ins and idioms seem, at first blush, to fly in the face of object-oriented principles, but are actually providing access to the objects with a functional syntax. In this chapter, we’ll discuss how the for statement is actually a lightweight wrapper around a set of object-oriented design patterns. We’ll also see a variety of extensions to this syntax that automatically create even more types of object. We will cover the following topics:
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What design patterns are
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The iterator protocol — one of the most powerful design patterns
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List, set, and dictionary comprehensions
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Generator functions, and how they build on other patterns
We’ll start with an overview of what design patterns are and why they’re so important.
