Software Design by Example in Python 13: A Code Linter

The HTML validator example in Chapter 11 has two natural follow-ons. the template expander of Chapter 12 (discussed [yesterday][template_post]) and a linter that checks whether the source of a Python program obeys a set of rules. Of these, I think the second is more important: the original lint utility on Unix helped me learn how to write C properly, and I now set up ruff before writing the first line of Python in a new project.

One thing that surprised me as I was writing Chapter 13: A Code Linter was how few new ideas it needed to introduce. By this point in the book, readers have walked trees using the Visitor pattern and understand that a program is just a data structure in memory. Putting those two things together was a lot easier than I feared it would be; in a way, the fact that the concept map below is smaller than most of its predecessors is a sign that I’ve put topics in the right (or “a” right) order.

Note: I would be grateful for help getting the book to display properly in dark mode. In particular, if you have a tool that will convert the SVG produced by draw.io to white-on-black and some CSS to select them in place of the black-on-white versions, please get in touch.

Terms defined: false negative, linter.