Python: Journey from Novice to Expert

Chapter 9. The Iterator Pattern

We've discussed how many of Python's built-ins and idioms that seem, at first blush, to be non-object-oriented are actually providing access to major objects under the hood. In this chapter, we'll discuss how the for loop that seems so structured is actually a lightweight wrapper around a set of object-oriented principles. We'll also see a variety of extensions to this syntax that automatically create even more types of object. We will cover:

• What design patterns are
• The iterator protocol—one of the most powerful design patterns
• List, set, and dictionary comprehensions
• Generators and coroutines

Design patterns in brief

When engineers and architects decide to build a bridge, or a tower, or a building, they follow certain ...