ruff config file

2025 Vertis

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13-11-2024

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The Ruff Configuration File: Tailoring Your Python Code Style

Ruff, a lightning-fast Python code formatter and linter, is a popular choice for developers who prioritize speed and consistency. But with great power comes great responsibility! To ensure your code conforms to your team's standards and preferences, understanding and configuring Ruff's settings is crucial.

This article will guide you through Ruff's configuration file and empower you to tailor your Python code style.

Ruff's Configuration: An Introduction

Ruff uses a configuration file, typically named .ruff.toml, to define the rules and styles your code should adhere to. This file acts as a blueprint for your code's formatting and linting.

Mastering the Ruff Configuration File

1. Configuration Options:

The .ruff.toml file is written in TOML format, a simple and easy-to-read configuration language. Here's an example of a basic .ruff.toml file:

[tool.ruff]
line-length = 100
target-version = ["py38", "py39"]
select = ["E", "W", "F", "I"]
ignore = ["E501"] # Ignore line length warnings (for demonstration)

Let's break down the key options:

• line-length: Sets the maximum line length (default 88 characters).
• target-version: Specifies the Python versions you are targeting. This impacts the rules Ruff enforces.
• select: Determines which code style categories to check.
  • E: Errors
  • W: Warnings
  • F: Flakes
  • I: PyLint
• ignore: Allows you to disable specific rules by their error codes.

2. Configuration Sources:

Ruff supports multiple configuration sources to allow for flexibility:

• ruff.toml (local): Your primary configuration file, specific to your project.
• pyproject.toml (project): If a pyproject.toml exists in your project's root, Ruff will look for a [tool.ruff] section within it.
• setup.cfg (project): Another commonly used project configuration file.
• ~/.config/ruff/ruff.toml (global): This file is used for global defaults that apply to all projects.

3. Advanced Configuration:

Ruff offers granular control over individual rules. You can specify the severity level for each rule (e.g., error, warning, info, ignore) and modify options specific to the rule itself.

Example:

[tool.ruff.pycodestyle]
line-length = 120 # Set the line length for pycodestyle

[tool.ruff.flake8]
max-line-length = 120 # Set the line length for flake8 rules

This example overrides the default line length for both pycodestyle and flake8 rules within the .ruff.toml file.

Best Practices for Configuration

• Start with defaults: Use Ruff's default configuration as a foundation and gradually customize it to meet your specific requirements.
• Comment clearly: Add comments to your .ruff.toml file explaining the rationale behind your configuration choices.
• Be consistent: Maintain consistency across your project and team members' configurations for a cohesive codebase.
• Use specific rules: Leverage Ruff's extensive rule set to enforce specific coding conventions tailored to your project.
• Utilize code style guides: Refer to popular Python style guides like PEP 8 for inspiration and guidance on configuring Ruff effectively.

Harnessing Ruff's Configuration Power

By understanding Ruff's configuration file, you can effectively control and standardize your Python code style. Experiment with different settings, tailor your code formatting and linting to your needs, and ensure a consistent and high-quality codebase.

Remember: While Ruff's configuration offers extensive options, it's essential to prioritize clarity, readability, and maintainability in your code.