Best practice for code style

Scripting
1

Lately I worked on a project that enforces flake8 conformance. And I learned to embrace it and think it is a good idea to use it for my own projects, too.

What is flake8

flake8 is a code analyzer that check if the code conforms to the pep8 rules.

Setup

As usual, there are some rules that I don’t like (e.g. line length). But thankfully, it is possible to configure this. This is done by adding a file .flake8 in the root of your repo, or even in its parent folder, if you have a lot repos.
Mine looks like this:

[flake8]
ignore = W191 E501 E722 W503

And if you use Visual Studio Code (it has extension for flake8 and shows the results inline, I find that very useful, (but if anyone knows an other IDE that can do that, too?).
this is my settings file (.vscode/settings.json):

{
	"editor.insertSpaces": false,
	"editor.formatOnSave": false,
	"editor.formatOnType": false,
	"flake8.args": [
		"--ignore=W191,E501,E722,W503",
		"--verbose"
	],
}

But flake8 can be run from the command line, too.

Why all that

All this is mostly about code formatting, readability and such. But there are a few things that flake8 can find that are real bugs. The most important is F821. But F841 is also useful.

Automatic Code Formatting

I found one tool that is highly configureable and thous the most useful for me: autopep8.

I use this prompt in the terminal:

autopep8 --in-place --select E221,E226,E225,E201,E202,E302,E305,E251,E261,W292,W293 path/to/file.py

or with the -r argument followed by a path to a folder. That will process all files in that folder.

autopep8 --in-place --select E221,E226,E225,E201,E202,E302,E305,E251,E261,W292,W293 -r path/to/folder

This will only tough issues with the peps in the command. Feel free do add/remove things.

2

Other very widely used code formatters are

  • Black

and quite new, but incredibly fast and rising in popularity:

  • Ruff

Both can also be set in VSCode to execute on file save, which is amazing, as it feels like a rubberband snapping your code-edits into tidyness right away. With Ruff (written in Rust) you can also ditch Pylance. Black is not very customizable, which is a deliberate descision by the developers and works well for most people. Ruff has more options to be customized, but the default is perfect for most users.

3

Thank you for posting your thoughts.

I agree that a fixed code style is a good thing, especially for collaborative projects (and possible collaborative projects like open source code).

The black formatter seems to be the standard across the usual Python suspects these days: fontTools, ufo2ft, fontmake, …

4

I know of black. But I’m too stubborn to let go of tabs :wink: and sometimes a list is nicer to be on one line, or all items one its own, and black will always reformat this.

5

Spaces:
I also hate spaces instead of tabs, but funnily since using auto formatters, I don’t care at all anymore. I still hit my tab key for indentation and just let go. Ease of mind. :love_you_gesture::melting_face::love_you_gesture:

Lists:
Black only formats lists to multiple lines, if you add a trailing comma (which most of us usually do). But if you really need a one-line-list, remove the last comma.
If the list exceeds a certain length though, it will always wrap. But I find that a good style.

6

One thing I forgot to mention is to only import what’s needed. So not from GlyphsApp import Glyphs. Or import vanilla and then use self.w = vanilla.Window().