Learning Python, 6th Edition

Chapter 19. Function Odds and Ends

This chapter presents a medley of function-related topics: recursive functions; function attributes, annotations, and decorations; and more on both the lambda expression and functional-programming tools such as map and filter. These are all somewhat advanced tools that, depending on your job description, you may not encounter on a regular basis. Because of their roles in some domains, though, a basic understanding can be useful. lambda, for instance, makes regular appearances in GUIs, and functional programming techniques have grown common in Python code.

Some of the art of using functions lies in the interfaces between them, so we will also explore some general function design principles here. The next chapter continues the advanced themes here with an exploration of generator functions and expressions and a revival of list comprehensions in the context of the functional tools we will study here.

Function Design Concepts

Now that we’ve studied function essentials in Python, let’s open this chapter with some perspective. When you start using functions in earnest, you’re faced with choices about how to glue components together—for instance, how to decompose a task into purposeful functions (known as cohesion), and how your functions should communicate (called coupling). You also need to take note of the size of your functions because it directly impacts code usability. Some of this falls into the category of structured analysis and design, but ...