Ruff in a Nutshell + Configuring it on VsCode

It explains Ruff and how to set up in VsCode
Ruff
Python
VsCode
Linter
Author

Guilherme Parreira

Published

September 1, 2024

Hello guys!

Today I want to talk about RUFF, my default formatter (and much more) for Python language.

In a nutshell, RUFF can be seen as a tool that performs all these tasks:

RUFF = Flake8 + isort + black + pydocstyle + pyupgrade + autoflake

Flake8 = Linter, which reports style + syntax errors

isort = Sort the imports

black = formatter ; mostly PEP8 compliant, but with a default line-length of 88 instead of PEP 8’s 79. It handles single/double quotes, empty lines and parentheses

pydocstyle = docstrings

pyupgrade = upgrade syntax for newer python versions

autoflake = Remove unused imports and unused variables

So, instead of having to set up each one individually, use RUFF and have all these tools into a single one. RUFF was written in rust, so it is not a wrap of the previously mentioned. Also, it is way faster than the previous tools.

Setting it up on VsCode

To give suggestions on the fly, I use the Ruff VsCode Extension.

Besides that, I have my settings.json with my personal preferences:

// Use Ruff as the default formatter for Python files
"[python]": {
"editor.defaultFormatter": "charliermarsh.ruff",
"editor.codeActionsOnSave": {
    "source.fixAll": "explicit",
    "source.organizeImports": "explicit"
}
},
// Formatter for notebook cells
"[jupyter]": {
"editor.defaultFormatter": "charliermarsh.ruff"
},
// Enable format on save for notebooks
"notebook.formatOnSave.enabled": true,
"editor.formatOnSave": true,

But these are only global settings in my personal environment.

Working with others on the same project can be painful if you don’t have a default formatter (because other team members can have different formatters and specifications); as a result, code may change the formatting for a new user. Therefore, having a .vscode/settings.json inside of the folder of your project guarantees that everyone will use the same formatter. For that, just copy your personal settings to .vscode/settings.json.

I also make Ruff as a default extension in .vscode/extensions.json:

{
    "recommendations": [
        "charliermarsh.ruff"
    ]
}

Last but not least, you can also install ruff in your environment and implement it on your CI/CD routines. But it will not be covered here. Installing the extension and using the .vscode/settings.json guarantees that the suggestions will be made on the fly. But it depends on your IDE and that everyone from your team uses it.

Bonus (Caveat)

I struggled to start using a tool like this because I used to write code in a single long line. I always received the E501: line-too-long warning from pycodestyle/Flake8. It happens when a line is longer than 79 characters, which is the recommendation in PEP 8 (ruff, like black, uses a slightly larger default of 88 characters). After applying a tool like ruff my code changed drastically (as it would force me to break lines), and it was uncomfortable in the beginning. So, I started to relax the parameter of the line-length a little bit (from the default to, for example, 150 characters) and started to analyze the impact of change. Then I realized that the impact on my previous code was not large at all.

Leaving the limit as the default, PEP 8 argues that you can open multiple files side by side, making also easier to see the git diff changes.

Anyway, if you think that this limit is small, you can relax it a little bit globally, doing it by:

[tool.ruff]
line-length = 130 # E501 (line-too-long) now only warns above 130 characters

lint.ignore = [
    "E701", # Ignore single-line if statements
]
lint.extend-select = ["D"] # Enable the docstring rules (pydocstyle), which are off by default
extend-include = ["*.ipynb"]

[tool.ruff.format]
quote-style = "double"
docstring-code-format = true

[tool.ruff.lint.pydocstyle] # Docstring style that the "D" rules check against
convention = "google"

Or, if you only want to keep a few specific lines as they are:

  • Add # noqa: E501 at the end of a line, so the linter stops warning that it is too long.
  • Add # fmt: skip at the end of a line, so the formatter does not reformat it.
  • Wrap a block of code between # fmt: off and # fmt: on, so the formatter leaves the whole block untouched.

Happy coding.

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