Generator Functions

Overview

Generator functions embody the essential features of a generator expression, which is the generalization of a comprehension. The generator function syntax looks even less object-oriented than anything we’ve seen, but we’ll discover that once again, it is a syntax shortcut to create a kind of iterator object. It helps us build processing following the standard iterator-filter-mapping pattern.

Example 1: Sprawling code

Let’s take the log file example a little further. If we want to decompose the log into columns, we’ll have to do a more significant transformation as part of the mapping step. This will involve a regular expression to find the timestamp, the severity word, and the message as a whole. We’ll look at a number of solutions to this problem to show how generators and generator functions can be applied to create the objects we want.

Here’s a version, avoiding generator expressions entirely: