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An extremely fast Python linter, written in Rust.

Project description

Ruff

Ruff image image image Actions status

An extremely fast Python linter, written in Rust.

Shows a bar chart with benchmark results.

Linting the CPython codebase from scratch.

  • ⚡️ 10-100x faster than existing linters
  • 🐍 Installable via pip
  • 🤝 Python 3.11 compatibility
  • 🛠️ pyproject.toml support
  • 📦 Built-in caching, to avoid re-analyzing unchanged files
  • 🔧 Autofix support, for automatic error correction (e.g., automatically remove unused imports)
  • ⚖️ Near-parity with the built-in Flake8 rule set
  • 🔌 Native re-implementations of dozens of Flake8 plugins, like flake8-bugbear
  • ⌨️ First-party editor integrations for VS Code and more
  • 🌎 Monorepo-friendly, with hierarchical and cascading configuration

Ruff aims to be orders of magnitude faster than alternative tools while integrating more functionality behind a single, common interface.

Ruff can be used to replace Flake8 (plus a variety of plugins), isort, pydocstyle, yesqa, eradicate, pyupgrade, and autoflake, all while executing tens or hundreds of times faster than any individual tool.

Ruff goes beyond the responsibilities of a traditional linter, instead functioning as an advanced code transformation tool capable of upgrading type annotations, rewriting class definitions, sorting imports, and more.

Ruff is extremely actively developed and used in major open-source projects like:

Read the launch blog post.

Testimonials

Sebastián Ramírez, creator of FastAPI:

Ruff is so fast that sometimes I add an intentional bug in the code just to confirm it's actually running and checking the code.

Bryan Van de Ven, co-creator of Bokeh, original author of Conda:

Ruff is ~150-200x faster than flake8 on my machine, scanning the whole repo takes ~0.2s instead of ~20s. This is an enormous quality of life improvement for local dev. It's fast enough that I added it as an actual commit hook, which is terrific.

Tim Abbott, lead developer of Zulip:

This is just ridiculously fast... ruff is amazing.

Table of Contents

  1. Installation and Usage
  2. Configuration
  3. Supported Rules
    1. Pyflakes (F)
    2. pycodestyle (E, W)
    3. mccabe (C90)
    4. isort (I)
    5. pydocstyle (D)
    6. pyupgrade (UP)
    7. pep8-naming (N)
    8. flake8-2020 (YTT)
    9. flake8-annotations (ANN)
    10. flake8-bandit (S)
    11. flake8-blind-except (BLE)
    12. flake8-boolean-trap (FBT)
    13. flake8-bugbear (B)
    14. flake8-builtins (A)
    15. flake8-comprehensions (C4)
    16. flake8-debugger (T10)
    17. flake8-errmsg (EM)
    18. flake8-implicit-str-concat (ISC)
    19. flake8-import-conventions (ICN)
    20. flake8-print (T20)
    21. flake8-pytest-style (PT)
    22. flake8-quotes (Q)
    23. flake8-return (RET)
    24. flake8-simplify (SIM)
    25. flake8-tidy-imports (TID)
    26. flake8-unused-arguments (ARG)
    27. flake8-datetimez (DTZ)
    28. eradicate (ERA)
    29. pandas-vet (PD)
    30. pygrep-hooks (PGH)
    31. Pylint (PLC, PLE, PLR, PLW)
    32. flake8-pie (PIE)
    33. Ruff-specific rules (RUF)
  4. Editor Integrations
  5. FAQ
  6. Development
  7. Releases
  8. Benchmarks
  9. Reference
  10. License
  11. Contributing

Installation and Usage

Installation

Ruff is available as ruff on PyPI:

pip install ruff

Packaging status

For macOS Homebrew and Linuxbrew users, Ruff is also available as ruff on Homebrew:

brew install ruff

For Conda users, Ruff is also available as ruff on conda-forge:

conda install -c conda-forge ruff

For Arch Linux users, Ruff is also available as ruff on the official repositories:

pacman -S ruff

Usage

To run Ruff, try any of the following:

ruff path/to/code/to/check.py  # Run Ruff over `check.py`
ruff path/to/code/             # Run Ruff over all files in `/path/to/code` (and any subdirectories)
ruff path/to/code/*.py         # Run Ruff over all `.py` files in `/path/to/code`

You can run Ruff in --watch mode to automatically re-run on-change:

ruff path/to/code/ --watch

Ruff also works with pre-commit:

- repo: https://github.com/charliermarsh/ruff-pre-commit
  # Ruff version.
  rev: 'v0.0.216'
  hooks:
    - id: ruff
      # Respect `exclude` and `extend-exclude` settings.
      args: ["--force-exclude"]

Configuration

Ruff is configurable both via pyproject.toml and the command line. For a full list of configurable options, see the API reference.

If left unspecified, the default configuration is equivalent to:

[tool.ruff]
line-length = 88

# Enable Pyflakes `E` and `F` codes by default.
select = ["E", "F"]
ignore = []

# Exclude a variety of commonly ignored directories.
exclude = [
    ".bzr",
    ".direnv",
    ".eggs",
    ".git",
    ".hg",
    ".mypy_cache",
    ".nox",
    ".pants.d",
    ".ruff_cache",
    ".svn",
    ".tox",
    ".venv",
    "__pypackages__",
    "_build",
    "buck-out",
    "build",
    "dist",
    "node_modules",
    "venv",
]
per-file-ignores = {}

# Allow unused variables when underscore-prefixed.
dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"

# Assume Python 3.10.
target-version = "py310"

[tool.ruff.mccabe]
# Unlike Flake8, default to a complexity level of 10.
max-complexity = 10

As an example, the following would configure Ruff to: (1) avoid checking for line-length violations (E501); (2) never remove unused imports (F401); and (3) ignore import-at-top-of-file errors (E402) in __init__.py files:

[tool.ruff]
# Enable Pyflakes and pycodestyle rules.
select = ["E", "F"]

# Never enforce `E501` (line length violations).
ignore = ["E501"]

# Never try to fix `F401` (unused imports).
unfixable = ["F401"]

# Ignore `E402` (import violations) in all `__init__.py` files, and in `path/to/file.py`.
[tool.ruff.per-file-ignores]
"__init__.py" = ["E402"]
"path/to/file.py" = ["E402"]

Plugin configurations should be expressed as subsections, e.g.:

[tool.ruff]
# Add "Q" to the list of enabled codes.
select = ["E", "F", "Q"]

[tool.ruff.flake8-quotes]
docstring-quotes = "double"

Ruff mirrors Flake8's error code system, in which each error code consists of a one-to-three letter prefix, followed by three digits (e.g., F401). The prefix indicates that "source" of the error code (e.g., F for Pyflakes, E for pycodestyle, ANN for flake8-annotations). The set of enabled errors is determined by the select and ignore options, which support both the full error code (e.g., F401) and the prefix (e.g., F).

As a special-case, Ruff also supports the ALL error code, which enables all error codes. Note that some of the pydocstyle error codes are conflicting (e.g., D203 and D211) as they represent alternative docstring formats. Enabling ALL without further configuration may result in suboptimal behavior, especially for the pydocstyle plugin.

As an alternative to pyproject.toml, Ruff will also respect a ruff.toml file, which implements an equivalent schema (though the [tool.ruff] hierarchy can be omitted). For example, the pyproject.toml described above would be represented via the following ruff.toml:

# Enable Pyflakes and pycodestyle rules.
select = ["E", "F"]

# Never enforce `E501` (line length violations).
ignore = ["E501"]

# Always autofix, but never try to fix `F401` (unused imports).
fix = true
unfixable = ["F401"]

# Ignore `E402` (import violations) in all `__init__.py` files, and in `path/to/file.py`.
[per-file-ignores]
"__init__.py" = ["E402"]
"path/to/file.py" = ["E402"]

For a full list of configurable options, see the API reference.

Some common configuration settings can be provided via the command-line:

ruff path/to/code/ --select F401 --select F403

See ruff --help for more:

Ruff: An extremely fast Python linter.

Usage: ruff [OPTIONS] [FILES]...

Arguments:
  [FILES]...

Options:
      --config <CONFIG>
          Path to the `pyproject.toml` or `ruff.toml` file to use for configuration
  -v, --verbose
          Enable verbose logging
  -q, --quiet
          Only log errors
  -s, --silent
          Disable all logging (but still exit with status code "1" upon detecting errors)
  -e, --exit-zero
          Exit with status code "0", even upon detecting errors
  -w, --watch
          Run in watch mode by re-running whenever files change
      --fix
          Attempt to automatically fix lint errors
      --fix-only
          Fix any fixable lint errors, but don't report on leftover violations. Implies `--fix`
      --diff
          Avoid writing any fixed files back; instead, output a diff for each changed file to stdout
  -n, --no-cache
          Disable cache reads
      --isolated
          Ignore all configuration files
      --select <SELECT>
          Comma-separated list of rule codes to enable (or ALL, to enable all rules)
      --extend-select <EXTEND_SELECT>
          Like --select, but adds additional error codes on top of the selected ones
      --ignore <IGNORE>
          Comma-separated list of error codes to disable
      --extend-ignore <EXTEND_IGNORE>
          Like --ignore, but adds additional error codes on top of the ignored ones
      --exclude <EXCLUDE>
          List of paths, used to exclude files and/or directories from checks
      --extend-exclude <EXTEND_EXCLUDE>
          Like --exclude, but adds additional files and directories on top of the excluded ones
      --fixable <FIXABLE>
          List of error codes to treat as eligible for autofix. Only applicable when autofix itself is enabled (e.g., via `--fix`)
      --unfixable <UNFIXABLE>
          List of error codes to treat as ineligible for autofix. Only applicable when autofix itself is enabled (e.g., via `--fix`)
      --per-file-ignores <PER_FILE_IGNORES>
          List of mappings from file pattern to code to exclude
      --format <FORMAT>
          Output serialization format for error messages [env: RUFF_FORMAT=] [possible values: text, json, junit, grouped, github, gitlab]
      --stdin-filename <STDIN_FILENAME>
          The name of the file when passing it through stdin
      --cache-dir <CACHE_DIR>
          Path to the cache directory [env: RUFF_CACHE_DIR=]
      --show-source
          Show violations with source code
      --respect-gitignore
          Respect file exclusions via `.gitignore` and other standard ignore files
      --force-exclude
          Enforce exclusions, even for paths passed to Ruff directly on the command-line
      --update-check
          Enable or disable automatic update checks
      --dummy-variable-rgx <DUMMY_VARIABLE_RGX>
          Regular expression matching the name of dummy variables
      --target-version <TARGET_VERSION>
          The minimum Python version that should be supported
      --line-length <LINE_LENGTH>
          Set the line-length for length-associated checks and automatic formatting
      --max-complexity <MAX_COMPLEXITY>
          Maximum McCabe complexity allowed for a given function
      --add-noqa
          Enable automatic additions of `noqa` directives to failing lines
      --clean
          Clear any caches in the current directory or any subdirectories
      --explain <EXPLAIN>
          Explain a rule
      --show-files
          See the files Ruff will be run against with the current settings
      --show-settings
          See the settings Ruff will use to check a given Python file
  -h, --help
          Print help information
  -V, --version
          Print version information

pyproject.toml discovery

Similar to ESLint, Ruff supports hierarchical configuration, such that the "closest" pyproject.toml file in the directory hierarchy is used for every individual file, with all paths in the pyproject.toml file (e.g., exclude globs, src paths) being resolved relative to the directory containing the pyproject.toml file.

There are a few exceptions to these rules:

  1. In locating the "closest" pyproject.toml file for a given path, Ruff ignores any pyproject.toml files that lack a [tool.ruff] section.
  2. If a configuration file is passed directly via --config, those settings are used for across files. Any relative paths in that configuration file (like exclude globs or src paths) are resolved relative to the current working directory.
  3. If no pyproject.toml file is found in the filesystem hierarchy, Ruff will fall back to using a default configuration. If a user-specific configuration file exists at ${config_dir}/ruff/pyproject.toml, that file will be used instead of the default configuration, with ${config_dir} being determined via the dirs crate, and all relative paths being again resolved relative to the current working directory.
  4. Any pyproject.toml-supported settings that are provided on the command-line (e.g., via --select) will override the settings in every resolved configuration file.

Unlike ESLint, Ruff does not merge settings across configuration files; instead, the "closest" configuration file is used, and any parent configuration files are ignored. In lieu of this implicit cascade, Ruff supports an extend field, which allows you to inherit the settings from another pyproject.toml file, like so:

# Extend the `pyproject.toml` file in the parent directory.
extend = "../pyproject.toml"
# But use a different line length.
line-length = 100

All of the above rules apply equivalently to ruff.toml files. If Ruff detects both a ruff.toml and pyproject.toml file, it will defer to the ruff.toml.

Python file discovery

When passed a path on the command-line, Ruff will automatically discover all Python files in that path, taking into account the exclude and extend-exclude settings in each directory's pyproject.toml file.

By default, Ruff will also skip any files that are omitted via .ignore, .gitignore, .git/info/exclude, and global gitignore files (see: respect-gitignore).

Files that are passed to ruff directly are always checked, regardless of the above criteria. For example, ruff /path/to/excluded/file.py will always check file.py.

Ignoring errors

To omit a lint check entirely, add it to the "ignore" list via ignore or extend-ignore, either on the command-line or in your pyproject.toml file.

To ignore an error inline, Ruff uses a noqa system similar to Flake8. To ignore an individual error, add # noqa: {code} to the end of the line, like so:

# Ignore F841.
x = 1  # noqa: F841

# Ignore E741 and F841.
i = 1  # noqa: E741, F841

# Ignore _all_ errors.
x = 1  # noqa

Note that, for multi-line strings, the noqa directive should come at the end of the string, and will apply to the entire string, like so:

"""Lorem ipsum dolor sit amet.

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
"""  # noqa: E501

To ignore all errors across an entire file, Ruff supports Flake8's # flake8: noqa directive (or, equivalently, # ruff: noqa). Adding either of those directives to any part of a file will disable error reporting for the entire file.

For targeted exclusions across entire files (e.g., "Ignore all F841 violations in /path/to/file.py"), see the per-file-ignores configuration setting.

"Action Comments"

Ruff respects isort's "Action Comments" (# isort: skip_file, # isort: on, # isort: off, # isort: skip, and # isort: split), which enable selectively enabling and disabling import sorting for blocks of code and other inline configuration.

See the isort documentation for more.

Automating noqa Directives

Ruff supports several workflows to aid in noqa management.

First, Ruff provides a special error code, RUF100, to enforce that your noqa directives are "valid", in that the errors they say they ignore are actually being triggered on that line (and thus suppressed). You can run ruff /path/to/file.py --extend-select RUF100 to flag unused noqa directives.

Second, Ruff can automatically remove unused noqa directives via its autofix functionality. You can run ruff /path/to/file.py --extend-select RUF100 --fix to automatically remove unused noqa directives.

Third, Ruff can automatically add noqa directives to all failing lines. This is useful when migrating a new codebase to Ruff. You can run ruff /path/to/file.py --add-noqa to automatically add noqa directives to all failing lines, with the appropriate error codes.

Supported Rules

Regardless of the rule's origin, Ruff re-implements every rule in Rust as a first-party feature.

By default, Ruff enables all E and F error codes, which correspond to those built-in to Flake8.

The 🛠 emoji indicates that a rule is automatically fixable by the --fix command-line option.

Pyflakes (F)

For more, see Pyflakes on PyPI.

Code Name Message Fix
F401 UnusedImport ... imported but unused 🛠
F402 ImportShadowedByLoopVar Import ... from line 1 shadowed by loop variable
F403 ImportStarUsed from ... import * used; unable to detect undefined names
F404 LateFutureImport from __future__ imports must occur at the beginning of the file
F405 ImportStarUsage ... may be undefined, or defined from star imports: ...
F406 ImportStarNotPermitted from ... import * only allowed at module level
F407 FutureFeatureNotDefined Future feature ... is not defined
F501 PercentFormatInvalidFormat '...' % ... has invalid format string: ...
F502 PercentFormatExpectedMapping '...' % ... expected mapping but got sequence
F503 PercentFormatExpectedSequence '...' % ... expected sequence but got mapping
F504 PercentFormatExtraNamedArguments '...' % ... has unused named argument(s): ... 🛠
F505 PercentFormatMissingArgument '...' % ... is missing argument(s) for placeholder(s): ...
F506 PercentFormatMixedPositionalAndNamed '...' % ... has mixed positional and named placeholders
F507 PercentFormatPositionalCountMismatch '...' % ... has 4 placeholder(s) but 2 substitution(s)
F508 PercentFormatStarRequiresSequence '...' % ... * specifier requires sequence
F509 PercentFormatUnsupportedFormatCharacter '...' % ... has unsupported format character 'c'
F521 StringDotFormatInvalidFormat '...'.format(...) has invalid format string: ...
F522 StringDotFormatExtraNamedArguments '...'.format(...) has unused named argument(s): ... 🛠
F523 StringDotFormatExtraPositionalArguments '...'.format(...) has unused arguments at position(s): ...
F524 StringDotFormatMissingArguments '...'.format(...) is missing argument(s) for placeholder(s): ...
F525 StringDotFormatMixingAutomatic '...'.format(...) mixes automatic and manual numbering
F541 FStringMissingPlaceholders f-string without any placeholders 🛠
F601 MultiValueRepeatedKeyLiteral Dictionary key literal ... repeated 🛠
F602 MultiValueRepeatedKeyVariable Dictionary key ... repeated 🛠
F621 ExpressionsInStarAssignment Too many expressions in star-unpacking assignment
F622 TwoStarredExpressions Two starred expressions in assignment
F631 AssertTuple Assert test is a non-empty tuple, which is always True
F632 IsLiteral Use == to compare constant literals 🛠
F633 InvalidPrintSyntax Use of >> is invalid with print function
F634 IfTuple If test is a tuple, which is always True
F701 BreakOutsideLoop break outside loop
F702 ContinueOutsideLoop continue not properly in loop
F704 YieldOutsideFunction yield statement outside of a function
F706 ReturnOutsideFunction return statement outside of a function/method
F707 DefaultExceptNotLast An except block as not the last exception handler
F722 ForwardAnnotationSyntaxError Syntax error in forward annotation: ...
F811 RedefinedWhileUnused Redefinition of unused ... from line 1
F821 UndefinedName Undefined name ...
F822 UndefinedExport Undefined name ... in __all__
F823 UndefinedLocal Local variable ... referenced before assignment
F841 UnusedVariable Local variable ... is assigned to but never used 🛠
F842 UnusedAnnotation Local variable ... is annotated but never used
F901 RaiseNotImplemented raise NotImplemented should be raise NotImplementedError 🛠

pycodestyle (E, W)

For more, see pycodestyle on PyPI.

Code Name Message Fix
E401 MultipleImportsOnOneLine Multiple imports on one line
E402 ModuleImportNotAtTopOfFile Module level import not at top of file
E501 LineTooLong Line too long (89 > 88 characters)
E711 NoneComparison Comparison to None should be cond is None 🛠
E712 TrueFalseComparison Comparison to True should be cond is True 🛠
E713 NotInTest Test for membership should be not in 🛠
E714 NotIsTest Test for object identity should be is not 🛠
E721 TypeComparison Do not compare types, use isinstance()
E722 DoNotUseBareExcept Do not use bare except
E731 DoNotAssignLambda Do not assign a lambda expression, use a def 🛠
E741 AmbiguousVariableName Ambiguous variable name: ...
E742 AmbiguousClassName Ambiguous class name: ...
E743 AmbiguousFunctionName Ambiguous function name: ...
E902 IOError IOError: ...
E999 SyntaxError SyntaxError: ...
W292 NoNewLineAtEndOfFile No newline at end of file 🛠
W605 InvalidEscapeSequence Invalid escape sequence: '\c' 🛠

mccabe (C90)

For more, see mccabe on PyPI.

Code Name Message Fix
C901 FunctionIsTooComplex ... is too complex (10)

isort (I)

For more, see isort on PyPI.

Code Name Message Fix
I001 UnsortedImports Import block is un-sorted or un-formatted 🛠

pydocstyle (D)

For more, see pydocstyle on PyPI.

Code Name Message Fix
D100 PublicModule Missing docstring in public module
D101 PublicClass Missing docstring in public class
D102 PublicMethod Missing docstring in public method
D103 PublicFunction Missing docstring in public function
D104 PublicPackage Missing docstring in public package
D105 MagicMethod Missing docstring in magic method
D106 PublicNestedClass Missing docstring in public nested class
D107 PublicInit Missing docstring in __init__
D200 FitsOnOneLine One-line docstring should fit on one line
D201 NoBlankLineBeforeFunction No blank lines allowed before function docstring (found 1) 🛠
D202 NoBlankLineAfterFunction No blank lines allowed after function docstring (found 1) 🛠
D203 OneBlankLineBeforeClass 1 blank line required before class docstring 🛠
D204 OneBlankLineAfterClass 1 blank line required after class docstring 🛠
D205 BlankLineAfterSummary 1 blank line required between summary line and description (found 2) 🛠
D206 IndentWithSpaces Docstring should be indented with spaces, not tabs
D207 NoUnderIndentation Docstring is under-indented 🛠
D208 NoOverIndentation Docstring is over-indented 🛠
D209 NewLineAfterLastParagraph Multi-line docstring closing quotes should be on a separate line 🛠
D210 NoSurroundingWhitespace No whitespaces allowed surrounding docstring text 🛠
D211 NoBlankLineBeforeClass No blank lines allowed before class docstring 🛠
D212 MultiLineSummaryFirstLine Multi-line docstring summary should start at the first line
D213 MultiLineSummarySecondLine Multi-line docstring summary should start at the second line
D214 SectionNotOverIndented Section is over-indented ("Returns") 🛠
D215 SectionUnderlineNotOverIndented Section underline is over-indented ("Returns") 🛠
D300 UsesTripleQuotes Use """triple double quotes"""
D301 UsesRPrefixForBackslashedContent Use r""" if any backslashes in a docstring
D400 EndsInPeriod First line should end with a period 🛠
D402 NoSignature First line should not be the function's signature
D403 FirstLineCapitalized First word of the first line should be properly capitalized
D404 NoThisPrefix First word of the docstring should not be "This"
D405 CapitalizeSectionName Section name should be properly capitalized ("returns") 🛠
D406 NewLineAfterSectionName Section name should end with a newline ("Returns") 🛠
D407 DashedUnderlineAfterSection Missing dashed underline after section ("Returns") 🛠
D408 SectionUnderlineAfterName Section underline should be in the line following the section's name ("Returns") 🛠
D409 SectionUnderlineMatchesSectionLength Section underline should match the length of its name ("Returns") 🛠
D410 BlankLineAfterSection Missing blank line after section ("Returns") 🛠
D411 BlankLineBeforeSection Missing blank line before section ("Returns") 🛠
D412 NoBlankLinesBetweenHeaderAndContent No blank lines allowed between a section header and its content ("Returns") 🛠
D413 BlankLineAfterLastSection Missing blank line after last section ("Returns") 🛠
D414 NonEmptySection Section has no content ("Returns")
D415 EndsInPunctuation First line should end with a period, question mark, or exclamation point 🛠
D416 SectionNameEndsInColon Section name should end with a colon ("Returns") 🛠
D417 DocumentAllArguments Missing argument descriptions in the docstring: x, y
D418 SkipDocstring Function decorated with @overload shouldn't contain a docstring
D419 NonEmpty Docstring is empty

pyupgrade (UP)

For more, see pyupgrade on PyPI.

Code Name Message Fix
UP001 UselessMetaclassType __metaclass__ = type is implied 🛠
UP003 TypeOfPrimitive Use str instead of type(...) 🛠
UP004 UselessObjectInheritance Class ... inherits from object 🛠
UP005 DeprecatedUnittestAlias assertEquals is deprecated, use assertEqual 🛠
UP006 UsePEP585Annotation Use list instead of List for type annotations 🛠
UP007 UsePEP604Annotation Use X | Y for type annotations 🛠
UP008 SuperCallWithParameters Use super() instead of super(__class__, self) 🛠
UP009 PEP3120UnnecessaryCodingComment UTF-8 encoding declaration is unnecessary 🛠
UP010 UnnecessaryFutureImport Unnecessary __future__ import ... for target Python version 🛠
UP011 UnnecessaryLRUCacheParams Unnecessary parameters to functools.lru_cache 🛠
UP012 UnnecessaryEncodeUTF8 Unnecessary call to encode as UTF-8 🛠
UP013 ConvertTypedDictFunctionalToClass Convert ... from TypedDict functional to class syntax 🛠
UP014 ConvertNamedTupleFunctionalToClass Convert ... from NamedTuple functional to class syntax 🛠
UP015 RedundantOpenModes Unnecessary open mode parameters 🛠
UP016 RemoveSixCompat Unnecessary six compatibility usage 🛠
UP017 DatetimeTimezoneUTC Use datetime.UTC alias 🛠
UP018 NativeLiterals Unnecessary call to str 🛠
UP019 TypingTextStrAlias typing.Text is deprecated, use str 🛠
UP020 OpenAlias Use builtin open 🛠
UP021 ReplaceUniversalNewlines universal_newlines is deprecated, use text 🛠
UP022 ReplaceStdoutStderr Sending stdout and stderr to pipe is deprecated, use capture_output 🛠
UP023 RewriteCElementTree cElementTree is deprecated, use ElementTree 🛠
UP024 OSErrorAlias Replace aliased errors with OSError 🛠
UP025 RewriteUnicodeLiteral Remove unicode literals from strings 🛠
UP026 RewriteMockImport mock is deprecated, use unittest.mock 🛠
UP027 RewriteListComprehension Replace unpacked list comprehension with a generator expression 🛠
UP028 RewriteYieldFrom Replace yield over for loop with yield from 🛠
UP029 UnnecessaryBuiltinImport Unnecessary builtin import: ... 🛠

pep8-naming (N)

For more, see pep8-naming on PyPI.

Code Name Message Fix
N801 InvalidClassName Class name ... should use CapWords convention
N802 InvalidFunctionName Function name ... should be lowercase
N803 InvalidArgumentName Argument name ... should be lowercase
N804 InvalidFirstArgumentNameForClassMethod First argument of a class method should be named cls
N805 InvalidFirstArgumentNameForMethod First argument of a method should be named self
N806 NonLowercaseVariableInFunction Variable ... in function should be lowercase
N807 DunderFunctionName Function name should not start and end with __
N811 ConstantImportedAsNonConstant Constant ... imported as non-constant ...
N812 LowercaseImportedAsNonLowercase Lowercase ... imported as non-lowercase ...
N813 CamelcaseImportedAsLowercase Camelcase ... imported as lowercase ...
N814 CamelcaseImportedAsConstant Camelcase ... imported as constant ...
N815 MixedCaseVariableInClassScope Variable mixedCase in class scope should not be mixedCase
N816 MixedCaseVariableInGlobalScope Variable mixedCase in global scope should not be mixedCase
N817 CamelcaseImportedAsAcronym Camelcase ... imported as acronym ...
N818 ErrorSuffixOnExceptionName Exception name ... should be named with an Error suffix

flake8-2020 (YTT)

For more, see flake8-2020 on PyPI.

Code Name Message Fix
YTT101 SysVersionSlice3Referenced sys.version[:3] referenced (python3.10), use sys.version_info
YTT102 SysVersion2Referenced sys.version[2] referenced (python3.10), use sys.version_info
YTT103 SysVersionCmpStr3 sys.version compared to string (python3.10), use sys.version_info
YTT201 SysVersionInfo0Eq3Referenced sys.version_info[0] == 3 referenced (python4), use >=
YTT202 SixPY3Referenced six.PY3 referenced (python4), use not six.PY2
YTT203 SysVersionInfo1CmpInt sys.version_info[1] compared to integer (python4), compare sys.version_info to tuple
YTT204 SysVersionInfoMinorCmpInt sys.version_info.minor compared to integer (python4), compare sys.version_info to tuple
YTT301 SysVersion0Referenced sys.version[0] referenced (python10), use sys.version_info
YTT302 SysVersionCmpStr10 sys.version compared to string (python10), use sys.version_info
YTT303 SysVersionSlice1Referenced sys.version[:1] referenced (python10), use sys.version_info

flake8-annotations (ANN)

For more, see flake8-annotations on PyPI.

Code Name Message Fix
ANN001 MissingTypeFunctionArgument Missing type annotation for function argument ...
ANN002 MissingTypeArgs Missing type annotation for *...
ANN003 MissingTypeKwargs Missing type annotation for **...
ANN101 MissingTypeSelf Missing type annotation for ... in method
ANN102 MissingTypeCls Missing type annotation for ... in classmethod
ANN201 MissingReturnTypePublicFunction Missing return type annotation for public function ...
ANN202 MissingReturnTypePrivateFunction Missing return type annotation for private function ...
ANN204 MissingReturnTypeSpecialMethod Missing return type annotation for special method ... 🛠
ANN205 MissingReturnTypeStaticMethod Missing return type annotation for staticmethod ...
ANN206 MissingReturnTypeClassMethod Missing return type annotation for classmethod ...
ANN401 DynamicallyTypedExpression Dynamically typed expressions (typing.Any) are disallowed in ...

flake8-bandit (S)

For more, see flake8-bandit on PyPI.

Code Name Message Fix
S101 AssertUsed Use of assert detected
S102 ExecUsed Use of exec detected
S103 BadFilePermissions os.chmod setting a permissive mask 0o777 on file or directory
S104 HardcodedBindAllInterfaces Possible binding to all interfaces
S105 HardcodedPasswordString Possible hardcoded password: "..."
S106 HardcodedPasswordFuncArg Possible hardcoded password: "..."
S107 HardcodedPasswordDefault Possible hardcoded password: "..."
S108 HardcodedTempFile Probable insecure usage of temporary file or directory: "..."
S113 RequestWithoutTimeout Probable use of requests call without timeout
S324 HashlibInsecureHashFunction Probable use of insecure hash functions in hashlib: "..."
S501 RequestWithNoCertValidation Probable use of ... call with verify=False disabling SSL certificate checks
S506 UnsafeYAMLLoad Probable use of unsafe yaml.load. Allows instantiation of arbitrary objects. Consider yaml.safe_load.

flake8-blind-except (BLE)

For more, see flake8-blind-except on PyPI.

Code Name Message Fix
BLE001 BlindExcept Do not catch blind exception: Exception

flake8-boolean-trap (FBT)

For more, see flake8-boolean-trap on PyPI.

Code Name Message Fix
FBT001 BooleanPositionalArgInFunctionDefinition Boolean positional arg in function definition
FBT002 BooleanDefaultValueInFunctionDefinition Boolean default value in function definition
FBT003 BooleanPositionalValueInFunctionCall Boolean positional value in function call

flake8-bugbear (B)

For more, see flake8-bugbear on PyPI.

Code Name Message Fix
B002 UnaryPrefixIncrement Python does not support the unary prefix increment
B003 AssignmentToOsEnviron Assigning to os.environ doesn't clear the environment
B004 UnreliableCallableCheck Using hasattr(x, '__call__') to test if x is callable is unreliable. Use callable(x) for consistent results.
B005 StripWithMultiCharacters Using .strip() with multi-character strings is misleading the reader
B006 MutableArgumentDefault Do not use mutable data structures for argument defaults
B007 UnusedLoopControlVariable Loop control variable i not used within the loop body 🛠
B008 FunctionCallArgumentDefault Do not perform function call in argument defaults
B009 GetAttrWithConstant Do not call getattr with a constant attribute value. It is not any safer than normal property access. 🛠
B010 SetAttrWithConstant Do not call setattr with a constant attribute value. It is not any safer than normal property access. 🛠
B011 DoNotAssertFalse Do not assert False (python -O removes these calls), raise AssertionError() 🛠
B012 JumpStatementInFinally return/continue/break inside finally blocks cause exceptions to be silenced
B013 RedundantTupleInExceptionHandler A length-one tuple literal is redundant. Write except ValueError instead of except (ValueError,). 🛠
B014 DuplicateHandlerException Exception handler with duplicate exception: ValueError 🛠
B015 UselessComparison Pointless comparison. This comparison does nothing but waste CPU instructions. Either prepend assert or remove it.
B016 CannotRaiseLiteral Cannot raise a literal. Did you intend to return it or raise an Exception?
B017 NoAssertRaisesException assertRaises(Exception) should be considered evil
B018 UselessExpression Found useless expression. Either assign it to a variable or remove it.
B019 CachedInstanceMethod Use of functools.lru_cache or functools.cache on methods can lead to memory leaks
B020 LoopVariableOverridesIterator Loop control variable ... overrides iterable it iterates
B021 FStringDocstring f-string used as docstring. This will be interpreted by python as a joined string rather than a docstring.
B022 UselessContextlibSuppress No arguments passed to contextlib.suppress. No exceptions will be suppressed and therefore this context manager is redundant
B023 FunctionUsesLoopVariable Function definition does not bind loop variable ...
B024 AbstractBaseClassWithoutAbstractMethod ... is an abstract base class, but it has no abstract methods
B025 DuplicateTryBlockException try-except block with duplicate exception Exception
B026 StarArgUnpackingAfterKeywordArg Star-arg unpacking after a keyword argument is strongly discouraged
B027 EmptyMethodWithoutAbstractDecorator ... is an empty method in an abstract base class, but has no abstract decorator
B904 RaiseWithoutFromInsideExcept Within an except clause, raise exceptions with raise ... from err or raise ... from None to distinguish them from errors in exception handling
B905 ZipWithoutExplicitStrict zip() without an explicit strict= parameter

flake8-builtins (A)

For more, see flake8-builtins on PyPI.

Code Name Message Fix
A001 BuiltinVariableShadowing Variable ... is shadowing a python builtin
A002 BuiltinArgumentShadowing Argument ... is shadowing a python builtin
A003 BuiltinAttributeShadowing Class attribute ... is shadowing a python builtin

flake8-comprehensions (C4)

For more, see flake8-comprehensions on PyPI.

Code Name Message Fix
C400 UnnecessaryGeneratorList Unnecessary generator (rewrite as a list comprehension) 🛠
C401 UnnecessaryGeneratorSet Unnecessary generator (rewrite as a set comprehension) 🛠
C402 UnnecessaryGeneratorDict Unnecessary generator (rewrite as a dict comprehension) 🛠
C403 UnnecessaryListComprehensionSet Unnecessary list comprehension (rewrite as a set comprehension) 🛠
C404 UnnecessaryListComprehensionDict Unnecessary list comprehension (rewrite as a dict comprehension) 🛠
C405 UnnecessaryLiteralSet Unnecessary (list|tuple) literal (rewrite as a set literal) 🛠
C406 UnnecessaryLiteralDict Unnecessary (list|tuple) literal (rewrite as a dict literal) 🛠
C408 UnnecessaryCollectionCall Unnecessary (dict|list|tuple) call (rewrite as a literal) 🛠
C409 UnnecessaryLiteralWithinTupleCall Unnecessary (list|tuple) literal passed to tuple() (remove the outer call to tuple()) 🛠
C410 UnnecessaryLiteralWithinListCall Unnecessary (list|tuple) literal passed to list() (rewrite as a list literal) 🛠
C411 UnnecessaryListCall Unnecessary list call (remove the outer call to list()) 🛠
C413 UnnecessaryCallAroundSorted Unnecessary (list|reversed) call around sorted() 🛠
C414 UnnecessaryDoubleCastOrProcess Unnecessary (list|reversed|set|sorted|tuple) call within (list|set|sorted|tuple)()
C415 UnnecessarySubscriptReversal Unnecessary subscript reversal of iterable within (reversed|set|sorted)()
C416 UnnecessaryComprehension Unnecessary (list|set) comprehension (rewrite using (list|set)()) 🛠
C417 UnnecessaryMap Unnecessary map usage (rewrite using a (list|set|dict) comprehension)

flake8-debugger (T10)

For more, see flake8-debugger on PyPI.

Code Name Message Fix
T100 Debugger Import for ... found

flake8-errmsg (EM)

For more, see flake8-errmsg on PyPI.

Code Name Message Fix
EM101 RawStringInException Exception must not use a string literal, assign to variable first
EM102 FStringInException Exception must not use an f-string literal, assign to variable first
EM103 DotFormatInException Exception must not use a .format() string directly, assign to variable first

flake8-implicit-str-concat (ISC)

For more, see flake8-implicit-str-concat on PyPI.

Code Name Message Fix
ISC001 SingleLineImplicitStringConcatenation Implicitly concatenated string literals on one line
ISC002 MultiLineImplicitStringConcatenation Implicitly concatenated string literals over continuation line
ISC003 ExplicitStringConcatenation Explicitly concatenated string should be implicitly concatenated

flake8-import-conventions (ICN)

Code Name Message Fix
ICN001 ImportAliasIsNotConventional ... should be imported as ...

flake8-print (T20)

For more, see flake8-print on PyPI.

Code Name Message Fix
T201 PrintFound print found 🛠
T203 PPrintFound pprint found 🛠

flake8-pytest-style (PT)

For more, see flake8-pytest-style on PyPI.

Code Name Message Fix
PT001 IncorrectFixtureParenthesesStyle Use @pytest.fixture() over @pytest.fixture 🛠
PT002 FixturePositionalArgs Configuration for fixture ... specified via positional args, use kwargs
PT003 ExtraneousScopeFunction scope='function' is implied in @pytest.fixture()
PT004 MissingFixtureNameUnderscore Fixture ... does not return anything, add leading underscore 🛠
PT005 IncorrectFixtureNameUnderscore Fixture ... returns a value, remove leading underscore 🛠
PT006 ParametrizeNamesWrongType Wrong name(s) type in @pytest.mark.parametrize, expected tuple 🛠
PT007 ParametrizeValuesWrongType Wrong values type in @pytest.mark.parametrize expected list of tuple
PT008 PatchWithLambda Use return_value= instead of patching with lambda
PT009 UnittestAssertion Use a regular assert instead of unittest-style ... 🛠
PT010 RaisesWithoutException set the expected exception in pytest.raises()
PT011 RaisesTooBroad pytest.raises(...) is too broad, set the match parameter or use a more specific exception
PT012 RaisesWithMultipleStatements pytest.raises() block should contain a single simple statement
PT013 IncorrectPytestImport Found incorrect import of pytest, use simple import pytest instead
PT015 AssertAlwaysFalse Assertion always fails, replace with pytest.fail()
PT016 FailWithoutMessage No message passed to pytest.fail()
PT017 AssertInExcept Found assertion on exception ... in except block, use pytest.raises() instead
PT018 CompositeAssertion Assertion should be broken down into multiple parts
PT019 FixtureParamWithoutValue Fixture ... without value is injected as parameter, use @pytest.mark.usefixtures instead
PT020 DeprecatedYieldFixture @pytest.yield_fixture is deprecated, use @pytest.fixture
PT021 FixtureFinalizerCallback Use yield instead of request.addfinalizer
PT022 UselessYieldFixture No teardown in fixture ..., use return instead of yield 🛠
PT023 IncorrectMarkParenthesesStyle Use @pytest.mark.... over @pytest.mark....() 🛠
PT024 UnnecessaryAsyncioMarkOnFixture pytest.mark.asyncio is unnecessary for fixtures 🛠
PT025 ErroneousUseFixturesOnFixture pytest.mark.usefixtures has no effect on fixtures 🛠
PT026 UseFixturesWithoutParameters Useless pytest.mark.usefixtures without parameters 🛠

flake8-quotes (Q)

For more, see flake8-quotes on PyPI.

Code Name Message Fix
Q000 BadQuotesInlineString Single quotes found but double quotes preferred
Q001 BadQuotesMultilineString Single quote multiline found but double quotes preferred
Q002 BadQuotesDocstring Single quote docstring found but double quotes preferred
Q003 AvoidQuoteEscape Change outer quotes to avoid escaping inner quotes

flake8-return (RET)

For more, see flake8-return on PyPI.

Code Name Message Fix
RET501 UnnecessaryReturnNone Do not explicitly return None in function if it is the only possible return value 🛠
RET502 ImplicitReturnValue Do not implicitly return None in function able to return non-None value 🛠
RET503 ImplicitReturn Missing explicit return at the end of function able to return non-None value 🛠
RET504 UnnecessaryAssign Unnecessary variable assignment before return statement
RET505 SuperfluousElseReturn Unnecessary else after return statement
RET506 SuperfluousElseRaise Unnecessary else after raise statement
RET507 SuperfluousElseContinue Unnecessary else after continue statement
RET508 SuperfluousElseBreak Unnecessary else after break statement

flake8-simplify (SIM)

For more, see flake8-simplify on PyPI.

Code Name Message Fix
SIM101 DuplicateIsinstanceCall Multiple isinstance calls for ..., merge into a single call 🛠
SIM102 NestedIfStatements Use a single if statement instead of nested if statements
SIM103 ReturnBoolConditionDirectly Return the condition ... directly 🛠
SIM105 UseContextlibSuppress Use contextlib.suppress(...) instead of try-except-pass
SIM107 ReturnInTryExceptFinally Don't use return in try/except and finally
SIM108 UseTernaryOperator Use ternary operator ... instead of if-else-block 🛠
SIM109 CompareWithTuple Use value in (..., ...) instead of value == ... or value == ... 🛠
SIM110 ConvertLoopToAny Use return any(x for x in y) instead of for loop 🛠
SIM111 ConvertLoopToAll Use return all(x for x in y) instead of for loop 🛠
SIM117 MultipleWithStatements Use a single with statement with multiple contexts instead of nested with statements
SIM118 KeyInDict Use key in dict instead of key in dict.keys() 🛠
SIM201 NegateEqualOp Use left != right instead of not left == right 🛠
SIM202 NegateNotEqualOp Use left == right instead of not left != right 🛠
SIM208 DoubleNegation Use expr instead of not (not expr) 🛠
SIM210 IfExprWithTrueFalse Use bool(expr) instead of True if expr else False 🛠
SIM211 IfExprWithFalseTrue Use not expr instead of False if expr else True 🛠
SIM212 IfExprWithTwistedArms Use b if b else a instead of a if not b else b 🛠
SIM220 AAndNotA Use False instead of ... and not ... 🛠
SIM221 AOrNotA Use True instead of ... or not ... 🛠
SIM222 OrTrue Use True instead of ... or True 🛠
SIM223 AndFalse Use False instead of ... and False 🛠
SIM300 YodaConditions Yoda conditions are discouraged, use left == right instead 🛠

flake8-tidy-imports (TID)

For more, see flake8-tidy-imports on PyPI.

Code Name Message Fix
TID251 BannedApi ... is banned: ...
TID252 BannedRelativeImport Relative imports are banned

flake8-unused-arguments (ARG)

For more, see flake8-unused-arguments on PyPI.

Code Name Message Fix
ARG001 UnusedFunctionArgument Unused function argument: ...
ARG002 UnusedMethodArgument Unused method argument: ...
ARG003 UnusedClassMethodArgument Unused class method argument: ...
ARG004 UnusedStaticMethodArgument Unused static method argument: ...
ARG005 UnusedLambdaArgument Unused lambda argument: ...

flake8-datetimez (DTZ)

For more, see flake8-datetimez on PyPI.

Code Name Message Fix
DTZ001 CallDatetimeWithoutTzinfo The use of datetime.datetime() without tzinfo argument is not allowed
DTZ002 CallDatetimeToday The use of datetime.datetime.today() is not allowed
DTZ003 CallDatetimeUtcnow The use of datetime.datetime.utcnow() is not allowed
DTZ004 CallDatetimeUtcfromtimestamp The use of datetime.datetime.utcfromtimestamp() is not allowed
DTZ005 CallDatetimeNowWithoutTzinfo The use of datetime.datetime.now() without tz argument is not allowed
DTZ006 CallDatetimeFromtimestamp The use of datetime.datetime.fromtimestamp() without tz argument is not allowed
DTZ007 CallDatetimeStrptimeWithoutZone The use of datetime.datetime.strptime() without %z must be followed by .replace(tzinfo=)
DTZ011 CallDateToday The use of datetime.date.today() is not allowed.
DTZ012 CallDateFromtimestamp The use of datetime.date.fromtimestamp() is not allowed

eradicate (ERA)

For more, see eradicate on PyPI.

Code Name Message Fix
ERA001 CommentedOutCode Found commented-out code 🛠

pandas-vet (PD)

For more, see pandas-vet on PyPI.

Code Name Message Fix
PD002 UseOfInplaceArgument inplace=True should be avoided; it has inconsistent behavior
PD003 UseOfDotIsNull .isna is preferred to .isnull; functionality is equivalent
PD004 UseOfDotNotNull .notna is preferred to .notnull; functionality is equivalent
PD007 UseOfDotIx .ix is deprecated; use more explicit .loc or .iloc
PD008 UseOfDotAt Use .loc instead of .at. If speed is important, use numpy.
PD009 UseOfDotIat Use .iloc instead of .iat. If speed is important, use numpy.
PD010 UseOfDotPivotOrUnstack .pivot_table is preferred to .pivot or .unstack; provides same functionality
PD011 UseOfDotValues Use .to_numpy() instead of .values
PD012 UseOfDotReadTable .read_csv is preferred to .read_table; provides same functionality
PD013 UseOfDotStack .melt is preferred to .stack; provides same functionality
PD015 UseOfPdMerge Use .merge method instead of pd.merge function. They have equivalent functionality.
PD901 DfIsABadVariableName df is a bad variable name. Be kinder to your future self.

pygrep-hooks (PGH)

For more, see pygrep-hooks on GitHub.

Code Name Message Fix
PGH001 NoEval No builtin eval() allowed
PGH002 DeprecatedLogWarn warn is deprecated in favor of warning
PGH003 BlanketTypeIgnore Use specific error codes when ignoring type issues
PGH004 BlanketNOQA Use specific error codes when using noqa

Pylint (PLC, PLE, PLR, PLW)

For more, see Pylint on PyPI.

Code Name Message Fix
PLC0414 UselessImportAlias Import alias does not rename original package 🛠
PLC2201 MisplacedComparisonConstant Comparison should be ... 🛠
PLC3002 UnnecessaryDirectLambdaCall Lambda expression called directly. Execute the expression inline instead.
PLE0117 NonlocalWithoutBinding Nonlocal name ... found without binding
PLE0118 UsedPriorGlobalDeclaration Name ... is used prior to global declaration on line 1
PLE1142 AwaitOutsideAsync await should be used within an async function
PLR0206 PropertyWithParameters Cannot have defined parameters for properties
PLR0402 ConsiderUsingFromImport Use from ... import ... in lieu of alias
PLR1701 ConsiderMergingIsinstance Merge these isinstance calls: isinstance(..., (...))
PLR1722 UseSysExit Use sys.exit() instead of exit 🛠
PLW0120 UselessElseOnLoop Else clause on loop without a break statement, remove the else and de-indent all the code inside it
PLW0602 GlobalVariableNotAssigned Using global for ... but no assignment is done

flake8-pie (PIE)

For more, see flake8-pie on PyPI.

Code Name Message Fix
PIE790 NoUnnecessaryPass Unnecessary pass statement 🛠
PIE794 DupeClassFieldDefinitions Class field ... is defined multiple times 🛠
PIE807 PreferListBuiltin Prefer list() over useless lambda 🛠

Ruff-specific rules (RUF)

Code Name Message Fix
RUF001 AmbiguousUnicodeCharacterString String contains ambiguous unicode character '𝐁' (did you mean 'B'?) 🛠
RUF002 AmbiguousUnicodeCharacterDocstring Docstring contains ambiguous unicode character '𝐁' (did you mean 'B'?) 🛠
RUF003 AmbiguousUnicodeCharacterComment Comment contains ambiguous unicode character '𝐁' (did you mean 'B'?) 🛠
RUF004 KeywordArgumentBeforeStarArgument Keyword argument ... must come after starred arguments
RUF100 UnusedNOQA Unused blanket noqa directive 🛠

Editor Integrations

VS Code (Official)

Download the Ruff VS Code extension, which supports autofix actions, import sorting, and more.

Language Server Protocol (Official)

Ruff supports the Language Server Protocol via the ruff-lsp Python package, available on PyPI.

ruff-lsp enables Ruff to be used with any editor that supports the Language Server Protocol, including Neovim, Sublime Text, Emacs, and more.

For example, to use ruff-lsp with Neovim, install ruff-lsp from PyPI along with nvim-lspconfig. Then, add something like the following to your init.lua:

-- See: https://github.com/neovim/nvim-lspconfig/tree/54eb2a070a4f389b1be0f98070f81d23e2b1a715#suggested-configuration
local opts = { noremap=true, silent=true }
vim.keymap.set('n', '<space>e', vim.diagnostic.open_float, opts)
vim.keymap.set('n', '[d', vim.diagnostic.goto_prev, opts)
vim.keymap.set('n', ']d', vim.diagnostic.goto_next, opts)
vim.keymap.set('n', '<space>q', vim.diagnostic.setloclist, opts)

-- Use an on_attach function to only map the following keys
-- after the language server attaches to the current buffer
local on_attach = function(client, bufnr)
  -- Enable completion triggered by <c-x><c-o>
  vim.api.nvim_buf_set_option(bufnr, 'omnifunc', 'v:lua.vim.lsp.omnifunc')

  -- Mappings.
  -- See `:help vim.lsp.*` for documentation on any of the below functions
  local bufopts = { noremap=true, silent=true, buffer=bufnr }
  vim.keymap.set('n', 'gD', vim.lsp.buf.declaration, bufopts)
  vim.keymap.set('n', 'gd', vim.lsp.buf.definition, bufopts)
  vim.keymap.set('n', 'K', vim.lsp.buf.hover, bufopts)
  vim.keymap.set('n', 'gi', vim.lsp.buf.implementation, bufopts)
  vim.keymap.set('n', '<C-k>', vim.lsp.buf.signature_help, bufopts)
  vim.keymap.set('n', '<space>wa', vim.lsp.buf.add_workspace_folder, bufopts)
  vim.keymap.set('n', '<space>wr', vim.lsp.buf.remove_workspace_folder, bufopts)
  vim.keymap.set('n', '<space>wl', function()
    print(vim.inspect(vim.lsp.buf.list_workspace_folders()))
  end, bufopts)
  vim.keymap.set('n', '<space>D', vim.lsp.buf.type_definition, bufopts)
  vim.keymap.set('n', '<space>rn', vim.lsp.buf.rename, bufopts)
  vim.keymap.set('n', '<space>ca', vim.lsp.buf.code_action, bufopts)
  vim.keymap.set('n', 'gr', vim.lsp.buf.references, bufopts)
  vim.keymap.set('n', '<space>f', function() vim.lsp.buf.format { async = true } end, bufopts)
end

-- Configure `ruff-lsp`.
local configs = require 'lspconfig.configs'
if not configs.ruff_lsp then
  configs.ruff_lsp = {
    default_config = {
      cmd = { 'ruff-lsp' },
      filetypes = { 'python' },
      root_dir = require('lspconfig').util.find_git_ancestor,
      init_options = {
        settings = {
          args = {}
        }
      }
    }
  }
end
require('lspconfig').ruff_lsp.setup {
  on_attach = on_attach,
}

Upon successful installation, you should see Ruff's diagnostics surfaced directly in your editor:

Code Actions available in Neovim

To use ruff-lsp with other editors, including Sublime Text and Helix, see the ruff-lsp documentation.

Language Server Protocol (Unofficial)

Ruff is also available as the python-lsp-ruff plugin for python-lsp-server, both of which are installable from PyPI:

pip install python-lsp-server python-lsp-ruff

The LSP server can then be used with any editor that supports the Language Server Protocol.

For example, to use python-lsp-ruff with Neovim, add something like the following to your init.lua:

require'lspconfig'.pylsp.setup {
  settings = {
    pylsp = {
      plugins = {
        ruff = {
          enabled = true
        },
        pycodestyle = {
          enabled = false
        },
        pyflakes = {
          enabled = false
        },
        mccabe = {
          enabled = false
        }
      }
    }
  },
}

Vim & Neovim

Ruff can be integrated into any editor that supports the Language Server Protocol via ruff-lsp (see: Language Server Protocol), including Vim and Neovim.

It's recommended that you use ruff-lsp, the officially supported LSP server for Ruff.

However, Ruff is also available as part of the coc-pyright extension for coc.nvim.

Ruff can also be integrated via efm in just a few lines.
tools:
  python-ruff: &python-ruff
    lint-command: 'ruff --config ~/myconfigs/linters/ruff.toml --quiet ${INPUT}'
    lint-stdin: true
    lint-formats:
      - '%f:%l:%c: %m'
    format-command: 'ruff --stdin-filename ${INPUT} --config ~/myconfigs/linters/ruff.toml --fix --exit-zero --quiet -'
    format-stdin: true
For neovim users using null-ls, Ruff is already integrated.
local null_ls = require("null-ls")
local methods = require("null-ls.methods")
local helpers = require("null-ls.helpers")

local function ruff_fix()
    return helpers.make_builtin({
        name = "ruff",
        meta = {
            url = "https://github.com/charliermarsh/ruff/",
            description = "An extremely fast Python linter, written in Rust.",
        },
        method = methods.internal.FORMATTING,
        filetypes = { "python" },
        generator_opts = {
            command = "ruff",
            args = { "--fix", "-e", "-n", "--stdin-filename", "$FILENAME", "-" },
            to_stdin = true
        },
        factory = helpers.formatter_factory
    })
end

null_ls.setup({
    sources = {
        ruff_fix(),
        null_ls.builtins.diagnostics.ruff,
    }
})

PyCharm (External Tool)

Ruff can be installed as an External Tool in PyCharm. Open the Preferences pane, then navigate to "Tools", then "External Tools". From there, add a new tool with the following configuration:

Install Ruff as an External Tool

Ruff should then appear as a runnable action:

Ruff as a runnable action

PyCharm (Unofficial)

Ruff is also available as the Ruff plugin on the IntelliJ Marketplace (maintained by @koxudaxi).

GitHub Actions

GitHub Actions has everything you need to run Ruff out-of-the-box:

name: CI
on: push
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - name: Install Python
        uses: actions/setup-python@v4
        with:
          python-version: "3.11"
      - name: Install dependencies
        run: |
          python -m pip install --upgrade pip
          pip install ruff
      # Include `--format=github` to enable automatic inline annotations.
      - name: Run Ruff
        run: ruff --format=github .

FAQ

Is Ruff compatible with Black?

Yes. Ruff is compatible with Black out-of-the-box, as long as the line-length setting is consistent between the two.

As a project, Ruff is designed to be used alongside Black and, as such, will defer implementing stylistic lint rules that are obviated by autoformatting.

How does Ruff compare to Flake8?

(Coming from Flake8? Try flake8-to-ruff to automatically convert your existing configuration.)

Ruff can be used as a drop-in replacement for Flake8 when used (1) without or with a small number of plugins, (2) alongside Black, and (3) on Python 3 code.

Under those conditions, Ruff implements every rule in Flake8.

Ruff also re-implements some of the most popular Flake8 plugins and related code quality tools natively, including:

Note that, in some cases, Ruff uses different error code prefixes than would be found in the originating Flake8 plugins. For example, Ruff uses TID252 to represent the I252 rule from flake8-tidy-imports. This helps minimize conflicts across plugins and allows any individual plugin to be toggled on or off with a single (e.g.) --select TID, as opposed to --select I2 (to avoid conflicts with the isort rules, like I001).

Beyond the rule set, Ruff suffers from the following limitations vis-à-vis Flake8:

  1. Ruff does not yet support structural pattern matching.
  2. Flake8 has a plugin architecture and supports writing custom lint rules. (Instead, popular Flake8 plugins are re-implemented in Rust as part of Ruff itself.)

There are a few other minor incompatibilities between Ruff and the originating Flake8 plugins:

  • Ruff doesn't implement the "opinionated" lint rules from flake8-bugbear.
  • Depending on your project structure, Ruff and isort can differ in their detection of first-party code. (This is often solved by modifying the src property, e.g., to src = ["src"], if your code is nested in a src directory.)

How does Ruff compare to Pylint?

At time of writing, Pylint implements 409 total rules, while Ruff implements 224, of which at least 60 overlap with the Pylint rule set. Subjectively, Pylint tends to implement more rules based on type inference (e.g., validating the number of arguments in a function call).

Like Flake8, Pylint supports plugins (called "checkers"), while Ruff implements all checks natively.

Unlike Pylint, Ruff is capable of automatically fixing its own lint errors.

Pylint parity is being tracked in #689.

Which tools does Ruff replace?

Today, Ruff can be used to replace Flake8 when used with any of the following plugins:

Ruff can also replace isort, yesqa, eradicate, pygrep-hooks (#980), and a subset of the rules implemented in pyupgrade (#827).

If you're looking to use Ruff, but rely on an unsupported Flake8 plugin, feel free to file an Issue.

Do I need to install Rust to use Ruff?

Nope! Ruff is available as ruff on PyPI:

pip install ruff

Ruff ships with wheels for all major platforms, which enables pip to install Ruff without relying on Rust at all.

Can I write my own plugins for Ruff?

Ruff does not yet support third-party plugins, though a plugin system is within-scope for the project. See #283 for more.

How does Ruff's import sorting compare to isort?

Ruff's import sorting is intended to be nearly equivalent to isort when used profile = "black". (There are some minor differences in how Ruff and isort break ties between similar imports.)

Like isort, Ruff's import sorting is compatible with Black.

Ruff is less configurable than isort, but supports the known-first-party, known-third-party, extra-standard-library, and src settings, like so:

[tool.ruff]
select = [
    # Pyflakes
    "F",
    # Pycodestyle
    "E",
    "W",
    # isort
    "I001"
]
src = ["src", "tests"]

[tool.ruff.isort]
known-first-party = ["my_module1", "my_module2"]

Does Ruff support Jupyter Notebooks?

Ruff is integrated into nbQA, a tool for running linters and code formatters over Jupyter Notebooks.

After installing ruff and nbqa, you can run Ruff over a notebook like so:

> nbqa ruff Untitled.ipynb
Untitled.ipynb:cell_1:2:5: F841 Local variable `x` is assigned to but never used
Untitled.ipynb:cell_2:1:1: E402 Module level import not at top of file
Untitled.ipynb:cell_2:1:8: F401 `os` imported but unused
Found 3 error(s).
1 potentially fixable with the --fix option.

Does Ruff support NumPy- or Google-style docstrings?

Yes! To enable specific docstring convention, add the following to your pyproject.toml:

[tool.ruff.pydocstyle]
convention = "google"  # Accepts: "google", "numpy", or "pep257".

For example, if you're coming from flake8-docstrings, and your originating configuration uses --docstring-convention=numpy, you'd instead set convention = "numpy" in your pyproject.toml, as above.

Alongside convention, you'll want to explicitly enable the D error code class, like so:

[tool.ruff]
select = [
    "D",
]

[tool.ruff.pydocstyle]
convention = "google"

Setting a convention force-disables any rules that are incompatible with that convention, no matter how they're provided, which avoids accidental incompatibilities and simplifies configuration.

How can I tell what settings Ruff is using to check my code?

Run ruff /path/to/code.py --show-settings to view the resolved settings for a given file.

Development

Ruff is written in Rust (1.65.0). You'll need to install the Rust toolchain for development.

Assuming you have cargo installed, you can run:

cargo run resources/test/fixtures

For development, we use nightly Rust:

cargo +nightly fmt
cargo +nightly clippy --fix --workspace --all-targets --all-features -- -W clippy::pedantic
cargo +nightly test --all

Releases

Ruff is distributed on PyPI, and published via maturin.

See: .github/workflows/release.yaml.

Benchmarks

First, clone CPython. It's a large and diverse Python codebase, which makes it a good target for benchmarking.

git clone --branch 3.10 https://github.com/python/cpython.git resources/test/cpython

Add this pyproject.toml to the CPython directory:

[tool.ruff]
line-length = 88
extend-exclude = [
    "Lib/lib2to3/tests/data/bom.py",
    "Lib/lib2to3/tests/data/crlf.py",
    "Lib/lib2to3/tests/data/different_encoding.py",
    "Lib/lib2to3/tests/data/false_encoding.py",
    "Lib/lib2to3/tests/data/py2_test_grammar.py",
    "Lib/test/bad_coding2.py",
    "Lib/test/badsyntax_3131.py",
    "Lib/test/badsyntax_pep3120.py",
    "Lib/test/encoded_modules/module_iso_8859_1.py",
    "Lib/test/encoded_modules/module_koi8_r.py",
    "Lib/test/test_fstring.py",
    "Lib/test/test_grammar.py",
    "Lib/test/test_importlib/test_util.py",
    "Lib/test/test_named_expressions.py",
    "Lib/test/test_patma.py",
    "Lib/test/test_source_encoding.py",
    "Tools/c-analyzer/c_parser/parser/_delim.py",
    "Tools/i18n/pygettext.py",
    "Tools/test2to3/maintest.py",
    "Tools/test2to3/setup.py",
    "Tools/test2to3/test/test_foo.py",
    "Tools/test2to3/test2to3/hello.py",
]

Next, to benchmark the release build:

cargo build --release

hyperfine --ignore-failure --warmup 10 --runs 100 \
  "./target/release/ruff ./resources/test/cpython/ --no-cache" \
  "./target/release/ruff ./resources/test/cpython/"

Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
  Time (mean ± σ):     297.4 ms ±   4.9 ms    [User: 2460.0 ms, System: 67.2 ms]
  Range (min  max):   287.7 ms  312.1 ms    100 runs

  Warning: Ignoring non-zero exit code.

Benchmark 2: ./target/release/ruff ./resources/test/cpython/
  Time (mean ± σ):      79.6 ms ±   7.3 ms    [User: 59.7 ms, System: 356.1 ms]
  Range (min  max):    62.4 ms  111.2 ms    100 runs

  Warning: Ignoring non-zero exit code.

To benchmark against the ecosystem's existing tools:

hyperfine --ignore-failure --warmup 5 \
  "./target/release/ruff ./resources/test/cpython/ --no-cache" \
  "pylint --recursive=y resources/test/cpython/" \
  "pyflakes resources/test/cpython" \
  "autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython" \
  "pycodestyle resources/test/cpython" \
  "flake8 resources/test/cpython" \
  "python -m scripts.run_flake8 resources/test/cpython"

In order, these evaluate:

  • Ruff
  • Pylint
  • Pyflakes
  • autoflake
  • pycodestyle
  • Flake8
  • Flake8, with a hack to enable multiprocessing on macOS

(You can poetry install from ./scripts to create a working environment for the above.)

Benchmark 1: ./target/release/ruff ./resources/test/cpython/ --no-cache
  Time (mean ± σ):     297.9 ms ±   7.0 ms    [User: 2436.6 ms, System: 65.9 ms]
  Range (min  max):   289.9 ms  314.6 ms    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 2: pylint --recursive=y resources/test/cpython/
  Time (mean ± σ):     37.634 s ±  0.225 s    [User: 36.728 s, System: 0.853 s]
  Range (min  max):   37.201 s  38.106 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 3: pyflakes resources/test/cpython
  Time (mean ± σ):     40.950 s ±  0.449 s    [User: 40.688 s, System: 0.229 s]
  Range (min  max):   40.348 s  41.671 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 4: autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython
  Time (mean ± σ):     11.562 s ±  0.160 s    [User: 107.022 s, System: 1.143 s]
  Range (min  max):   11.417 s  11.917 s    10 runs

Benchmark 5: pycodestyle resources/test/cpython
  Time (mean ± σ):     67.428 s ±  0.985 s    [User: 67.199 s, System: 0.203 s]
  Range (min  max):   65.313 s  68.496 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 6: flake8 resources/test/cpython
  Time (mean ± σ):     116.099 s ±  1.178 s    [User: 115.217 s, System: 0.845 s]
  Range (min  max):   114.180 s  117.724 s    10 runs

  Warning: Ignoring non-zero exit code.

Benchmark 7: python -m scripts.run_flake8 resources/test/cpython
  Time (mean ± σ):     20.477 s ±  0.349 s    [User: 142.372 s, System: 1.504 s]
  Range (min  max):   20.107 s  21.183 s    10 runs

Summary
  './target/release/ruff ./resources/test/cpython/ --no-cache' ran
   38.81 ± 1.05 times faster than 'autoflake --recursive --expand-star-imports --remove-all-unused-imports --remove-unused-variables --remove-duplicate-keys resources/test/cpython'
   68.74 ± 1.99 times faster than 'python -m scripts.run_flake8 resources/test/cpython'
  126.33 ± 3.05 times faster than 'pylint --recursive=y resources/test/cpython/'
  137.46 ± 3.55 times faster than 'pyflakes resources/test/cpython'
  226.35 ± 6.23 times faster than 'pycodestyle resources/test/cpython'
  389.73 ± 9.92 times faster than 'flake8 resources/test/cpython'

Reference

Options

allowed-confusables

A list of allowed "confusable" Unicode characters to ignore when enforcing RUF001, RUF002, and RUF003.

Default value: []

Type: Vec<char>

Example usage:

[tool.ruff]
# Allow minus-sign (U+2212), greek-small-letter-rho (U+03C1), and the asterisk-operator (U+2217),
# which could be confused for "-", "p", and "*", respectively.
allowed-confusables = ["−", "ρ", "∗"]

builtins

A list of builtins to treat as defined references, in addition to the system builtins.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff]
builtins = ["_"]

cache-dir

A path to the cache directory.

By default, Ruff stores cache results in a .ruff_cache directory in the current project root.

However, Ruff will also respect the RUFF_CACHE_DIR environment variable, which takes precedence over that default.

This setting will override even the RUFF_CACHE_DIR environment variable, if set.

Default value: .ruff_cache

Type: PathBuf

Example usage:

[tool.ruff]
cache-dir = "~/.cache/ruff"

dummy-variable-rgx

A regular expression used to identify "dummy" variables, or those which should be ignored when evaluating (e.g.) unused-variable checks. The default expression matches _, __, and _var, but not _var_.

Default value: "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"

Type: Regex

Example usage:

[tool.ruff]
# Only ignore variables named "_".
dummy-variable-rgx = "^_$"

exclude

A list of file patterns to exclude from linting.

Exclusions are based on globs, and can be either:

  • Single-path patterns, like .mypy_cache (to exclude any directory named .mypy_cache in the tree), foo.py (to exclude any file named foo.py), or foo_*.py (to exclude any file matching foo_*.py ).
  • Relative patterns, like directory/foo.py (to exclude that specific file) or directory/*.py (to exclude any Python files in directory). Note that these paths are relative to the project root (e.g., the directory containing your pyproject.toml).

Note that you'll typically want to use extend-exclude to modify the excluded paths.

Default value: [".bzr", ".direnv", ".eggs", ".git", ".hg", ".mypy_cache", ".nox", ".pants.d", ".ruff_cache", ".svn", ".tox", ".venv", "__pypackages__", "_build", "buck-out", "build", "dist", "node_modules", "venv"]

Type: Vec<FilePattern>

Example usage:

[tool.ruff]
exclude = [".venv"]

extend

A path to a local pyproject.toml file to merge into this configuration. User home directory and environment variables will be expanded.

To resolve the current pyproject.toml file, Ruff will first resolve this base configuration file, then merge in any properties defined in the current configuration file.

Default value: None

Type: Path

Example usage:

[tool.ruff]
# Extend the `pyproject.toml` file in the parent directory.
extend = "../pyproject.toml"
# But use a different line length.
line-length = 100

extend-exclude

A list of file patterns to omit from linting, in addition to those specified by exclude.

Default value: []

Type: Vec<FilePattern>

Example usage:

[tool.ruff]
# In addition to the standard set of exclusions, omit all tests, plus a specific file.
extend-exclude = ["tests", "src/bad.py"]

extend-ignore

A list of check code prefixes to ignore, in addition to those specified by ignore.

Default value: []

Type: Vec<RuleCodePrefix>

Example usage:

[tool.ruff]
# Skip unused variable checks (`F841`).
extend-ignore = ["F841"]

extend-select

A list of check code prefixes to enable, in addition to those specified by select.

Default value: []

Type: Vec<RuleCodePrefix>

Example usage:

[tool.ruff]
# On top of the default `select` (`E`, `F`), enable flake8-bugbear (`B`) and flake8-quotes (`Q`).
extend-select = ["B", "Q"]

external

A list of check codes that are unsupported by Ruff, but should be preserved when (e.g.) validating # noqa directives. Useful for retaining # noqa directives that cover plugins not yet implemented by Ruff.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff]
# Avoiding flagging (and removing) `V101` from any `# noqa`
# directives, despite Ruff's lack of support for `vulture`.
external = ["V101"]

fix

Enable autofix behavior by-default when running ruff (overridden by the --fix and --no-fix command-line flags).

Default value: false

Type: bool

Example usage:

[tool.ruff]
fix = true

fix-only

Like fix, but disables reporting on leftover violation. Implies fix.

Default value: false

Type: bool

Example usage:

[tool.ruff]
fix-only = true

fixable

A list of check code prefixes to consider autofix-able.

Default value: ["A", "ANN", "ARG", "B", "BLE", "C", "D", "E", "ERA", "F", "FBT", "I", "ICN", "N", "PGH", "PLC", "PLE", "PLR", "PLW", "Q", "RET", "RUF", "S", "T", "TID", "UP", "W", "YTT"]

Type: Vec<RuleCodePrefix>

Example usage:

[tool.ruff]
# Only allow autofix behavior for `E` and `F` checks.
fixable = ["E", "F"]

force-exclude

Whether to enforce exclude and extend-exclude patterns, even for paths that are passed to Ruff explicitly. Typically, Ruff will lint any paths passed in directly, even if they would typically be excluded. Setting force-exclude = true will cause Ruff to respect these exclusions unequivocally.

This is useful for pre-commit, which explicitly passes all changed files to the ruff-pre-commit plugin, regardless of whether they're marked as excluded by Ruff's own settings.

Default value: false

Type: bool

Example usage:

[tool.ruff]
force-exclude = true

format

The style in which violation messages should be formatted: "text" (default), "grouped" (group messages by file), "json" (machine-readable), "junit" (machine-readable XML), "github" (GitHub Actions annotations) or "gitlab" (GitLab CI code quality report).

Default value: "text"

Type: SerializationType

Example usage:

[tool.ruff]
# Group violations by containing file.
format = "grouped"

ignore

A list of check code prefixes to ignore. Prefixes can specify exact checks (like F841), entire categories (like F), or anything in between.

When breaking ties between enabled and disabled checks (via select and ignore, respectively), more specific prefixes override less specific prefixes.

Default value: []

Type: Vec<RuleCodePrefix>

Example usage:

[tool.ruff]
# Skip unused variable checks (`F841`).
ignore = ["F841"]

ignore-init-module-imports

Avoid automatically removing unused imports in __init__.py files. Such imports will still be +flagged, but with a dedicated message suggesting that the import is either added to the module' +__all__ symbol, or re-exported with a redundant alias (e.g., import os as os).

Default value: false

Type: bool

Example usage:

[tool.ruff]
ignore-init-module-imports = true

line-length

The line length to use when enforcing long-lines violations (like E501).

Default value: 88

Type: usize

Example usage:

[tool.ruff]
# Allow lines to be as long as 120 characters.
line-length = 120

per-file-ignores

A list of mappings from file pattern to check code prefixes to exclude, when considering any matching files.

Default value: {}

Type: HashMap<String, Vec<RuleCodePrefix>>

Example usage:

[tool.ruff]
# Ignore `E402` (import violations) in all `__init__.py` files, and in `path/to/file.py`.
[tool.ruff.per-file-ignores]
"__init__.py" = ["E402"]
"path/to/file.py" = ["E402"]

required-version

Require a specific version of Ruff to be running (useful for unifying results across many environments, e.g., with a pyproject.toml file).

Default value: None

Type: String

Example usage:

[tool.ruff]
required-version = "0.0.193"

respect-gitignore

Whether to automatically exclude files that are ignored by .ignore, .gitignore, .git/info/exclude, and global gitignore files. Enabled by default.

Default value: true

Type: bool

Example usage:

[tool.ruff]
respect_gitignore = false

select

A list of check code prefixes to enable. Prefixes can specify exact checks (like F841), entire categories (like F), or anything in between.

When breaking ties between enabled and disabled checks (via select and ignore, respectively), more specific prefixes override less specific prefixes.

Default value: ["E", "F"]

Type: Vec<RuleCodePrefix>

Example usage:

[tool.ruff]
# On top of the defaults (`E`, `F`), enable flake8-bugbear (`B`) and flake8-quotes (`Q`).
select = ["E", "F", "B", "Q"]

show-source

Whether to show source code snippets when reporting lint error violations (overridden by the --show-source command-line flag).

Default value: false

Type: bool

Example usage:

[tool.ruff]
# By default, always show source code snippets.
show-source = true

src

The source code paths to consider, e.g., when resolving first- vs. third-party imports.

As an example: given a Python package structure like:

my_package/
  pyproject.toml
  src/
    my_package/
      __init__.py
      foo.py
      bar.py

The src directory should be included in source (e.g., source = ["src"]), such that when resolving imports, my_package.foo is considered a first-party import.

This field supports globs. For example, if you have a series of Python packages in a python_modules directory, src = ["python_modules/*"] would expand to incorporate all of the packages in that directory. User home directory and environment variables will also be expanded.

Default value: ["."]

Type: Vec<PathBuf>

Example usage:

[tool.ruff]
# Allow imports relative to the "src" and "test" directories.
src = ["src", "test"]

target-version

The Python version to target, e.g., when considering automatic code upgrades, like rewriting type annotations. Note that the target version will not be inferred from the current Python version, and instead must be specified explicitly (as seen below).

Default value: "py310"

Type: PythonVersion

Example usage:

[tool.ruff]
# Always generate Python 3.7-compatible code.
target-version = "py37"

task-tags

A list of task tags to recognize (e.g., "TODO", "FIXME", "XXX").

Comments starting with these tags will be ignored by commented-out code detection (ERA), and skipped by line-length checks (E501) if ignore-overlong-task-comments is set to true.

Default value: ["TODO", "FIXME", "XXX"]

Type: Vec<String>

Example usage:

[tool.ruff]
task-tags = ["HACK"]

unfixable

A list of check code prefixes to consider un-autofix-able.

Default value: []

Type: Vec<RuleCodePrefix>

Example usage:

[tool.ruff]
# Disable autofix for unused imports (`F401`).
unfixable = ["F401"]

update-check

Enable or disable automatic update checks (overridden by the --update-check and --no-update-check command-line flags).

Default value: true

Type: bool

Example usage:

[tool.ruff]
update-check = false

flake8-annotations

allow-star-arg-any

Whether to suppress ANN401 for dynamically typed *args and **kwargs arguments.

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-annotations]
allow-star-arg-any = true

mypy-init-return

Whether to allow the omission of a return type hint for __init__ if at least one argument is annotated.

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-annotations]
mypy-init-return = true

suppress-dummy-args

Whether to suppress ANN000-level errors for arguments matching the "dummy" variable regex (like _).

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-annotations]
suppress-dummy-args = true

suppress-none-returning

Whether to suppress ANN200-level errors for functions that meet either of the following criteria:

  • Contain no return statement.
  • Explicit return statement(s) all return None (explicitly or implicitly).

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-annotations]
suppress-none-returning = true

flake8-bandit

hardcoded-tmp-directory

A list of directories to consider temporary.

Default value: ["/tmp", "/var/tmp", "/dev/shm"]

Type: Vec<String>

Example usage:

[tool.ruff.flake8-bandit]
hardcoded-tmp-directory = ["/foo/bar"]

hardcoded-tmp-directory-extend

A list of directories to consider temporary, in addition to those specified by hardcoded-tmp-directory.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.flake8-bandit]
extend-hardcoded-tmp-directory = ["/foo/bar"]

flake8-bugbear

extend-immutable-calls

Additional callable functions to consider "immutable" when evaluating, e.g., no-mutable-default-argument checks (B006).

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.flake8-bugbear]
# Allow default arguments like, e.g., `data: List[str] = fastapi.Query(None)`.
extend-immutable-calls = ["fastapi.Depends", "fastapi.Query"]

flake8-errmsg

max-string-length

Maximum string length for string literals in exception messages.

Default value: 0

Type: usize

Example usage:

[tool.ruff.flake8-errmsg]
max-string-length = 20

flake8-import-conventions

aliases

The conventional aliases for imports. These aliases can be extended by the extend_aliases option.

Default value: {"altair": "alt", "matplotlib.pyplot": "plt", "numpy": "np", "pandas": "pd", "seaborn": "sns"}

Type: FxHashMap<String, String>

Example usage:

[tool.ruff.flake8-import-conventions]
[tool.ruff.flake8-import-conventions.aliases]
# Declare the default aliases.
altair = "alt"
"matplotlib.pyplot" = "plt"
numpy = "np"
pandas = "pd"
seaborn = "sns"

extend-aliases

A mapping of modules to their conventional import aliases. These aliases will be added to the aliases mapping.

Default value: {}

Type: FxHashMap<String, String>

Example usage:

[tool.ruff.flake8-import-conventions]
[tool.ruff.flake8-import-conventions.extend-aliases]
# Declare a custom alias for the `matplotlib` module.
"dask.dataframe" = "dd"

flake8-pytest-style

fixture-parentheses

Boolean flag specifying whether @pytest.fixture() without parameters should have parentheses. If the option is set to true (the default), @pytest.fixture() is valid and @pytest.fixture is an error. If set to false, @pytest.fixture is valid and @pytest.fixture() is an error.

Default value: true

Type: bool

Example usage:

[tool.ruff.flake8-pytest-style]
fixture-parentheses = true

mark-parentheses

Boolean flag specifying whether @pytest.mark.foo() without parameters should have parentheses. If the option is set to true (the default), @pytest.mark.foo() is valid and @pytest.mark.foo is an error. If set to false, @pytest.fixture is valid and @pytest.mark.foo() is an error.

Default value: true

Type: bool

Example usage:

[tool.ruff.flake8-pytest-style]
mark-parentheses = true

parametrize-names-type

Expected type for multiple argument names in @pytest.mark.parametrize. The following values are supported:

  • csv — a comma-separated list, e.g. @pytest.mark.parametrize('name1,name2', ...)
  • tuple (default) — e.g. @pytest.mark.parametrize(('name1', 'name2'), ...)
  • list — e.g. @pytest.mark.parametrize(['name1', 'name2'], ...)

Default value: tuple

Type: ParametrizeNameType

Example usage:

[tool.ruff.flake8-pytest-style]
parametrize-names-type = "list"

parametrize-values-row-type

Expected type for each row of values in @pytest.mark.parametrize in case of multiple parameters. The following values are supported:

  • tuple (default) — e.g. @pytest.mark.parametrize(('name1', 'name2'), [(1, 2), (3, 4)])
  • list — e.g. @pytest.mark.parametrize(('name1', 'name2'), [[1, 2], [3, 4]])

Default value: tuple

Type: ParametrizeValuesRowType

Example usage:

[tool.ruff.flake8-pytest-style]
parametrize-values-row-type = "list"

parametrize-values-type

Expected type for the list of values rows in @pytest.mark.parametrize. The following values are supported:

  • tuple — e.g. @pytest.mark.parametrize('name', (1, 2, 3))
  • list (default) — e.g. @pytest.mark.parametrize('name', [1, 2, 3])

Default value: list

Type: ParametrizeValuesType

Example usage:

[tool.ruff.flake8-pytest-style]
parametrize-values-type = "tuple"

raises-extend-require-match-for

List of additional exception names that require a match= parameter in a pytest.raises() call. This extends the default list of exceptions that require a match= parameter. This option is useful if you want to extend the default list of exceptions that require a match= parameter without having to specify the entire list. Note that this option does not remove any exceptions from the default list.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.flake8-pytest-style]
raises-extend-require-match-for = ["requests.RequestException"]

raises-require-match-for

List of exception names that require a match= parameter in a pytest.raises() call.

Default value: ["BaseException", "Exception", "ValueError", "OSError", "IOError", "EnvironmentError", "socket.error"]

Type: Vec<String>

Example usage:

[tool.ruff.flake8-pytest-style]
raises-require-match-for = ["requests.RequestException"]

flake8-quotes

avoid-escape

Whether to avoid using single quotes if a string contains single quotes, or vice-versa with double quotes, as per PEP8. This minimizes the need to escape quotation marks within strings.

Default value: true

Type: bool

Example usage:

[tool.ruff.flake8-quotes]
# Don't bother trying to avoid escapes.
avoid-escape = false

docstring-quotes

Quote style to prefer for docstrings (either "single" (') or "double" (")).

Default value: "double"

Type: Quote

Example usage:

[tool.ruff.flake8-quotes]
docstring-quotes = "single"

inline-quotes

Quote style to prefer for inline strings (either "single" (') or "double" (")).

Default value: "double"

Type: Quote

Example usage:

[tool.ruff.flake8-quotes]
inline-quotes = "single"

multiline-quotes

Quote style to prefer for multiline strings (either "single" (') or "double" (")).

Default value: "double"

Type: Quote

Example usage:

[tool.ruff.flake8-quotes]
multiline-quotes = "single"

flake8-tidy-imports

ban-relative-imports

Whether to ban all relative imports ("all"), or only those imports that extend into the parent module or beyond ("parents").

Default value: "parents"

Type: Strictness

Example usage:

[tool.ruff.flake8-tidy-imports]
# Disallow all relative imports.
ban-relative-imports = "all"

banned-api

Specific modules or module members that may not be imported or accessed. Note that this check is only meant to flag accidental uses, and can be circumvented via eval or importlib.

Default value: {}

Type: HashMap<String, BannedApi>

Example usage:

[tool.ruff.flake8-tidy-imports]
[tool.ruff.flake8-tidy-imports.banned-api]
"cgi".msg = "The cgi module is deprecated, see https://peps.python.org/pep-0594/#cgi."
"typing.TypedDict".msg = "Use typing_extensions.TypedDict instead."

flake8-unused-arguments

ignore-variadic-names

Whether to allow unused variadic arguments, like *args and **kwargs.

Default value: false

Type: bool

Example usage:

[tool.ruff.flake8-unused-arguments]
ignore-variadic-names = true

isort

combine-as-imports

Combines as imports on the same line. See isort's combine-as-imports option.

Default value: false

Type: bool

Example usage:

[tool.ruff.isort]
combine-as-imports = true

extra-standard-library

A list of modules to consider standard-library, in addition to those known to Ruff in advance.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.isort]
extra-standard-library = ["path"]

force-single-line

Forces all from imports to appear on their own line.

Default value: false

Type: bool

Example usage:

[tool.ruff.isort]
force-single-line = true

force-sort-within-sections

Don't sort straight-style imports (like import sys) before from-style imports (like from itertools import groupby). Instead, sort the imports by module, independent of import style.

Default value: false

Type: bool

Example usage:

[tool.ruff.isort]
force-sort-within-sections = true

force-wrap-aliases

Force import from statements with multiple members and at least one alias (e.g., import A as B) to wrap such that every line contains exactly one member. For example, this formatting would be retained, rather than condensing to a single line:

from .utils import (
    test_directory as test_directory,
    test_id as test_id
)

Note that this setting is only effective when combined with combine-as-imports = true. When combine-as-imports isn't enabled, every aliased import from will be given its own line, in which case, wrapping is not necessary.

Default value: false

Type: bool

Example usage:

[tool.ruff.isort]
force-wrap-aliases = true
combine-as-imports = true

known-first-party

A list of modules to consider first-party, regardless of whether they can be identified as such via introspection of the local filesystem.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.isort]
known-first-party = ["src"]

known-third-party

A list of modules to consider third-party, regardless of whether they can be identified as such via introspection of the local filesystem.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.isort]
known-third-party = ["src"]

order-by-type

Order imports by type, which is determined by case, in addition to alphabetically.

Default value: true

Type: bool

Example usage:

[tool.ruff.isort]
order-by-type = true

single-line-exclusions

One or more modules to exclude from the single line rule.

Default value: []

Type: Vec<String>

Example usage:

[tool.ruff.isort]
single-line-exclusions = ["os", "json"]

split-on-trailing-comma

If a comma is placed after the last member in a multi-line import, then the imports will never be folded into one line.

See isort's split-on-trailing-comma option.

Default value: true

Type: bool

Example usage:

[tool.ruff.isort]
split-on-trailing-comma = false

mccabe

max-complexity

The maximum McCabe complexity to allow before triggering C901 errors.

Default value: 10

Type: usize

Example usage:

[tool.ruff.mccabe]
# Flag errors (`C901`) whenever the complexity level exceeds 5.
max-complexity = 5

pep8-naming

classmethod-decorators

A list of decorators that, when applied to a method, indicate that the method should be treated as a class method. For example, Ruff will expect that any method decorated by a decorator in this list takes a cls argument as its first argument.

Default value: ["classmethod"]

Type: Vec<String>

Example usage:

[tool.ruff.pep8-naming]
# Allow Pydantic's `@validator` decorator to trigger class method treatment.
classmethod-decorators = ["classmethod", "pydantic.validator"]

ignore-names

A list of names to ignore when considering pep8-naming violations.

Default value: ["setUp", "tearDown", "setUpClass", "tearDownClass", "setUpModule", "tearDownModule", "asyncSetUp", "asyncTearDown", "setUpTestData", "failureException", "longMessage", "maxDiff"]

Type: Vec<String>

Example usage:

[tool.ruff.pep8-naming]
ignore-names = ["callMethod"]

staticmethod-decorators

A list of decorators that, when applied to a method, indicate that the method should be treated as a static method. For example, Ruff will expect that any method decorated by a decorator in this list has no self or cls argument.

Default value: ["staticmethod"]

Type: Vec<String>

Example usage:

[tool.ruff.pep8-naming]
# Allow a shorthand alias, `@stcmthd`, to trigger static method treatment.
staticmethod-decorators = ["staticmethod", "stcmthd"]

pycodestyle

ignore-overlong-task-comments

Whether or not line-length checks (E501) should be triggered for comments starting with task-tags (by default: ["TODO", "FIXME", and "XXX"]).

Default value: false

Type: bool

Example usage:

[tool.ruff.pycodestyle]
ignore-overlong-task-comments = true

pydocstyle

convention

Whether to use Google-style or NumPy-style conventions or the PEP257 defaults when analyzing docstring sections.

Default value: None

Type: Convention

Example usage:

[tool.ruff.pydocstyle]
# Use Google-style docstrings.
convention = "google"

pyupgrade

keep-runtime-typing

Whether to avoid PEP 585 (List[int] -> list[int]) and PEP 604 (Optional[str] -> str | None) rewrites even if a file imports from __future__ import annotations. Note that this setting is only applicable when the target Python version is below 3.9 and 3.10 respectively.

Default value: false

Type: bool

Example usage:

[tool.ruff.pyupgrade]
# Preserve types, even if a file imports `from __future__ import annotations`.
keep-runtime-typing = true

License

MIT

Contributing

Contributions are welcome and hugely appreciated. To get started, check out the contributing guidelines.

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