Ruff

Ruff is a modern, high-performance tool for Python development that combines the functionality of a linter and a code formatter. Written in Rust, it is designed to be orders of magnitude faster than existing tools like Flake8, isort, and Black.

Info

Ruff’s primary goal is to provide a single, cohesive, and extremely fast tool that can replace a large number of other Python linters and formatters, simplifying project configuration and improving developer productivity.

Core Philosophy

• Performance: Be the fastest tool available for Python linting and formatting. By building in Rust, Ruff avoids the startup overhead of Python-based tools.
• Compatibility: Provide near-complete compatibility with the rules of popular tools like Flake8, pylint, isort, and pyupgrade.
• Consolidation: Offer a single executable and configuration file (ruff.toml or pyproject.toml) to manage linting, formatting, and import sorting.

Key Features

• Speed: Ruff can be 10-100 times faster than its Python-based counterparts.
• Extensive Rule Set: Implements hundreds of linting rules from various tools, which can be easily enabled and configured.
• Autofixing: Can automatically fix many of the issues it detects, from simple style violations to upgrading code syntax.
• Built-in Formatter: Includes a code formatter that is compatible with Black, allowing you to replace both your linter and formatter with a single tool.

Common Commands

# Check files for linting errors
ruff check .
 
# Check files and automatically fix what can be fixed
ruff check . --fix
 
# Format files
ruff format .
 
# Run both the linter (with autofix) and the formatter
ruff check . --fix && ruff format .

Configuration

Ruff is typically configured in your project’s pyproject.toml file.

# pyproject.toml
[tool.ruff]
# Same as Black.
line-length = 88
 
[tool.ruff.lint]
# Enable the default set of rules, plus some extras.
select = ["E", "F", "W", "I", "N"]
ignore = []
 
[tool.ruff.format]
# Python 3.8+ features allowed.
preview = true

Ruff has quickly become an essential tool in the modern Python ecosystem. Its incredible speed and unified approach to code quality dramatically improve the development feedback loop, making it a powerful replacement for a large collection of older tools.