Features

• Plugin architecture: Adding new checks is easy.

• Parseable output: Jump to error location in your editor.

• Small: Just one Python file, requires only stdlib. You can use just the pycodestyle.py file for this purpose.

• Comes with a comprehensive test suite.

Installation

You can install, upgrade, and uninstall pycodestyle.py with these commands:

$ pip install pycodestyle
$ pip install --upgrade pycodestyle
$ pip uninstall pycodestyle

There’s also a package for Debian/Ubuntu, but it’s not always the latest version.

Example usage and output

$ pycodestyle --first optparse.py
optparse.py:69:11: E401 multiple imports on one line
optparse.py:77:1: E302 expected 2 blank lines, found 1
optparse.py:88:5: E301 expected 1 blank line, found 0
optparse.py:222:34: W602 deprecated form of raising exception
optparse.py:347:31: E211 whitespace before '('
optparse.py:357:17: E201 whitespace after '{'
optparse.py:472:29: E221 multiple spaces before operator
optparse.py:544:21: W601 .has_key() is deprecated, use 'in'

You can also make pycodestyle.py show the source code for each error, and even the relevant text from PEP 8:

$ pycodestyle --show-source --show-pep8 testsuite/E40.py
testsuite/E40.py:2:10: E401 multiple imports on one line
import os, sys
         ^
    Imports should usually be on separate lines.

    Okay: import os\nimport sys
    E401: import sys, os

Or you can display how often each error was found:

$ pycodestyle --statistics -qq Python-2.5/Lib
232     E201 whitespace after '['
599     E202 whitespace before ')'
631     E203 whitespace before ','
842     E211 whitespace before '('
2531    E221 multiple spaces before operator
4473    E301 expected 1 blank line, found 0
4006    E302 expected 2 blank lines, found 1
165     E303 too many blank lines (4)
325     E401 multiple imports on one line
3615    E501 line too long (82 characters)
612     W601 .has_key() is deprecated, use 'in'
1188    W602 deprecated form of raising exception

Links

• Read the documentation

• Fork me on GitHub

2.6.0 (2020-05-11)

Announcements:

• Anthony Sottile (@asottile) joined the team as a core developer. :tada:

Changes:

• E306: fix detection inside async def. PR #929.

• E301: fix regression disallowing decorated one-liners. PR #927.

• E714: fix false positive with chained is not. PR #931.

2.6.0a1 (2020-04-23)

New checks:

• E225: require whitespace around and in is and or. PR #847.

Changes:

• E117: fix indentation using tabs by treating as 8-space indents. PR #837.

• E721: fix false positive with names containg istype. PR #850.

• E741: allow l as a named argument in a function call. PR #853.

• E302: fix false-negative with decorated functions. PR #859.

• W504: ellipsis (...) is no longer treated as a binary operator. PR #875.

• E402: allow with, if, elif, else to guard imports. PR #834.

• Add support for assignment expressions := (PEP 572). PR #879.

• Add support for positional-only arguments / (PEP 570). PR #872, #918.

• Add support for python 3.8.

• Add support for matrix multiplication operator @ (PEP 465). PR #897.

• Support visual indent for continuation lines for with / assert / raise. PR #912.

• E302: allow two blank lines after a block of one-liners. PR #913.

• E302: allow two-and-fewer newlines at the top of the file. PR #919.

2.5.0 (2019-01-29)

New checks:

• E117: Over-indented code blocks

• W505: Maximum doc-string length only when configured with –max-doc-length

Changes:

• Remove support for EOL Python 2.6 and 3.3. PR #720.

• Add E117 error for over-indented code blocks.

• Allow W605 to be silenced by # noqa and fix the position reported by W605

• Allow users to omit blank lines around one-liner definitions of classes and functions

• Include the function return annotation (->) as requiring surrounding whitespace only on Python 3

• Verify that only names can follow await. Previously we allowed numbers and strings.

• Add support for Python 3.7

• Fix detection of annotated argument defaults for E252

• Correct the position reported by W504

2.4.0 (2018-04-10)

New checks:

• Add W504 warning for checking that a break doesn’t happen after a binary operator. This check is ignored by default. PR #502.

• Add W605 warning for invalid escape sequences in string literals. PR #676.

• Add W606 warning for ‘async’ and ‘await’ reserved keywords being introduced in Python 3.7. PR #684.

• Add E252 error for missing whitespace around equal sign in type annotated function arguments with defaults values. PR #717.

Changes:

• An internal bisect search has replaced a linear search in order to improve efficiency. PR #648.

• pycodestyle now uses PyPI trove classifiers in order to document supported python versions on PyPI. PR #654.

• ‘setup.cfg’ ‘[wheel]’ section has been renamed to ‘[bdist_wheel]’, as the former is legacy. PR #653.

• pycodestyle now handles very long lines much more efficiently for python 3.2+. Fixes #643. PR #644.

• You can now write ‘pycodestyle.StyleGuide(verbose=True)’ instead of ‘pycodestyle.StyleGuide(verbose=True, paths=[‘-v’])’ in order to achieve verbosity. PR #663.

• The distribution of pycodestyle now includes the license text in order to comply with open source licenses which require this. PR #694.

• ‘maximum_line_length’ now ignores shebang (‘#!’) lines. PR #736.

• Add configuration option for the allowed number of blank lines. It is implemented as a top level dictionary which can be easily overwritten. Fixes #732. PR #733.

Bugs:

• Prevent a ‘DeprecationWarning’, and a ‘SyntaxError’ in future python, caused by an invalid escape sequence. PR #625.

• Correctly report E501 when the first line of a docstring is too long. Resolves #622. PR #630.

• Support variable annotation when variable start by a keyword, such as class variable type annotations in python 3.6. PR #640.

• pycodestyle internals have been changed in order to allow ‘python3 -m cProfile’ to report correct metrics. PR #647.

• Fix a spelling mistake in the description of E722. PR #697.

• ‘pycodestyle –diff’ now does not break if your ‘gitconfig’ enables ‘mnemonicprefix’. PR #706.

2.3.1 (2017-01-31)

Bugs:

• Fix regression in detection of E302 and E306; #618, #620

2.3.0 (2017-01-30)

New Checks:

• Add E722 warning for bare except clauses

• Report E704 for async function definitions (async def)

Bugs:

• Fix another E305 false positive for variables beginning with “class” or “def”

• Fix detection of multiple spaces between async and def

• Fix handling of variable annotations. Stop reporting E701 on Python 3.6 for variable annotations.

2.2.0 (2016-11-14)

Announcements:

• Added Make target to obtain proper tarball file permissions; #599

Bugs:

• Fixed E305 regression caused by #400; #593

2.1.0 (2016-11-04)

Announcements:

• Change all references to the pep8 project to say pycodestyle; #530

Changes:

• Report E302 for blank lines before an “async def”; #556

• Update our list of tested and supported Python versions which are 2.6, 2.7, 3.2, 3.3, 3.4 and 3.5 as well as the nightly Python build and PyPy.

• Report E742 and E743 for functions and classes badly named ‘l’, ‘O’, or ‘I’.

• Report E741 on ‘global’ and ‘nonlocal’ statements, as well as prohibited single-letter variables.

• Deprecated use of [pep8] section name in favor of [pycodestyle]; #591

• Report E722 when bare except clause is used; #579

Bugs:

• Fix opt_type AssertionError when using Flake8 2.6.2 and pycodestyle; #561

• Require two blank lines after toplevel def, class; #536

• Remove accidentally quadratic computation based on the number of colons. This will make pycodestyle faster in some cases; #314

2.0.0 (2016-05-31)

Announcements:

• Repository renamed to pycodestyle; Issue #466 / #481.

• Added joint Code of Conduct as member of PyCQA; #483

Changes:

• Added tox test support for Python 3.5 and pypy3

• Added check E275 for whitespace on from … import … lines; #489 / #491

• Added W503 to the list of codes ignored by default ignore list; #498

• Removed use of project level .pep8 configuration file; #364

Bugs:

• Fixed bug with treating ~ operator as binary; #383 / #384

• Identify binary operators as unary; #484 / #485

1.7.0 (2016-01-12)

Announcements:

• Repository moved to PyCQA Organization on GitHub: https://github.com/pycqa/pep8

Changes:

• Reverted the fix in #368, “options passed on command line are only ones accepted” feature. This has many unintended consequences in pep8 and flake8 and needs to be reworked when I have more time.

• Added support for Python 3.5. (Issue #420 & #459)

• Added support for multi-line config_file option parsing. (Issue #429)

• Improved parameter parsing. (Issues #420 & #456)

Bugs:

• Fixed BytesWarning on Python 3. (Issue #459)

1.6.2 (2015-02-15)

Changes:

• Added check for breaking around a binary operator. (Issue #197, Pull #305)

Bugs:

• Restored config_file parameter in process_options(). (Issue #380)

1.6.1 (2015-02-08)

Changes:

• Assign variables before referenced. (Issue #287)

Bugs:

• Exception thrown due to unassigned local_dir variable. (Issue #377)

1.6.0 (2015-02-06)

News:

• Ian Lee <ianlee1521@gmail.com> joined the project as a maintainer.

Changes:

• Report E731 for lambda assignment. (Issue #277)

• Report E704 for one-liner def instead of E701. Do not report this error in the default configuration. (Issue #277)

• Replace codes E111, E112 and E113 with codes E114, E115 and E116 for bad indentation of comments. (Issue #274)

• Report E266 instead of E265 when the block comment starts with multiple #. (Issue #270)

• Report E402 for import statements not at the top of the file. (Issue #264)

• Do not enforce whitespaces around ** operator. (Issue #292)

• Strip whitespace from around paths during normalization. (Issue #339 / #343)

• Update --format documentation. (Issue #198 / Pull Request #310)

• Add .tox/ to default excludes. (Issue #335)

• Do not report E121 or E126 in the default configuration. (Issues #256 / #316)

• Allow spaces around the equals sign in an annotated function. (Issue #357)

• Allow trailing backslash if in an inline comment. (Issue #374)

• If --config is used, only that configuration is processed. Otherwise, merge the user and local configurations are merged. (Issue #368 / #369)

Bug fixes:

• Don’t crash if Checker.build_tokens_line() returns None. (Issue #306)

• Don’t crash if os.path.expanduser() throws an ImportError. (Issue #297)

• Missing space around keyword parameter equal not always reported, E251. (Issue #323)

• Fix false positive E711/E712/E713. (Issues #330 and #336)

• Do not skip physical checks if the newline is escaped. (Issue #319)

• Flush sys.stdout to avoid race conditions with printing. See flake8 bug: https://gitlab.com/pycqa/flake8/issues/17 for more details. (Issue #363)

1.5.7 (2014-05-29)

Bug fixes:

• Skip the traceback on “Broken pipe” signal. (Issue #275)

• Do not exit when an option in setup.cfg or tox.ini is not recognized.

• Check the last line even if it does not end with a newline. (Issue #286)

• Always open files in universal newlines mode in Python 2. (Issue #288)

1.5.6 (2014-04-14)

Bug fixes:

• Check the last line even if it has no end-of-line. (Issue #273)

1.5.5 (2014-04-10)

Bug fixes:

• Fix regression with E22 checks and inline comments. (Issue #271)

1.5.4 (2014-04-07)

Bug fixes:

• Fix negative offset with E303 before a multi-line docstring. (Issue #269)

1.5.3 (2014-04-04)

Bug fixes:

• Fix wrong offset computation when error is on the last char of a physical line. (Issue #268)

1.5.2 (2014-04-04)

Changes:

• Distribute a universal wheel file.

Bug fixes:

• Report correct line number for E303 with comments. (Issue #60)

• Do not allow newline after parameter equal. (Issue #252)

• Fix line number reported for multi-line strings. (Issue #220)

• Fix false positive E121/E126 with multi-line strings. (Issue #265)

• Fix E501 not detected in comments with Python 2.5.

• Fix caret position with --show-source when line contains tabs.

1.5.1 (2014-03-27)

Bug fixes:

• Fix a crash with E125 on multi-line strings. (Issue #263)

1.5 (2014-03-26)

Changes:

• Report E129 instead of E125 for visually indented line with same indent as next logical line. (Issue #126)

• Report E265 for space before block comment. (Issue #190)

• Report E713 and E714 when operators not in and is not are recommended. (Issue #236)

• Allow long lines in multiline strings and comments if they cannot be wrapped. (Issue #224).

• Optionally disable physical line checks inside multiline strings, using # noqa. (Issue #242)

• Change text for E121 to report “continuation line under-indented for hanging indent” instead of indentation not being a multiple of 4.

• Report E131 instead of E121 / E126 if the hanging indent is not consistent within the same continuation block. It helps when error E121 or E126 is in the ignore list.

• Report E126 instead of E121 when the continuation line is hanging with extra indentation, even if indentation is not a multiple of 4.

Bug fixes:

• Allow the checkers to report errors on empty files. (Issue #240)

• Fix ignoring too many checks when --select is used with codes declared in a flake8 extension. (Issue #216)

• Fix regression with multiple brackets. (Issue #214)

• Fix StyleGuide to parse the local configuration if the keyword argument paths is specified. (Issue #246)

• Fix a false positive E124 for hanging indent. (Issue #254)

• Fix a false positive E126 with embedded colon. (Issue #144)

• Fix a false positive E126 when indenting with tabs. (Issue #204)

• Fix behaviour when exclude is in the configuration file and the current directory is not the project directory. (Issue #247)

• The logical checks can return None instead of an empty iterator. (Issue #250)

• Do not report multiple E101 if only the first indentation starts with a tab. (Issue #237)

• Fix a rare false positive W602. (Issue #34)

1.4.6 (2013-07-02)

Changes:

• Honor # noqa for errors E711 and E712. (Issue #180)

• When both a tox.ini and a setup.cfg are present in the project directory, merge their contents. The tox.ini file takes precedence (same as before). (Issue #182)

• Give priority to --select over --ignore. (Issue #188)

• Compare full path when excluding a file. (Issue #186)

• New option --hang-closing to switch to the alternative style of closing bracket indentation for hanging indent. Add error E133 for closing bracket which is missing indentation. (Issue #103)

• Accept both styles of closing bracket indentation for hanging indent. Do not report error E123 in the default configuration. (Issue #103)

Bug fixes:

• Do not crash when running AST checks and the document contains null bytes. (Issue #184)

• Correctly report other E12 errors when E123 is ignored. (Issue #103)

• Fix false positive E261/E262 when the file contains a BOM. (Issue #193)

• Fix E701, E702 and E703 not detected sometimes. (Issue #196)

• Fix E122 not detected in some cases. (Issue #201 and #208)

• Fix false positive E121 with multiple brackets. (Issue #203)

1.4.5 (2013-03-06)

• When no path is specified, do not try to read from stdin. The feature was added in 1.4.3, but it is not supported on Windows. Use - filename argument to read from stdin. This usage is supported since 1.3.4. (Issue #170)

• Do not require setuptools in setup.py. It works around an issue with pip and Python 3. (Issue #172)

• Add __pycache__ to the ignore list.

• Change misleading message for E251. (Issue #171)

• Do not report false E302 when the source file has a coding cookie or a comment on the first line. (Issue #174)

• Reorganize the tests and add tests for the API and for the command line usage and options. (Issues #161 and #162)

• Ignore all checks which are not explicitly selected when select is passed to the StyleGuide constructor.

1.4.4 (2013-02-24)

• Report E227 or E228 instead of E225 for whitespace around bitwise, shift or modulo operators. (Issue #166)

• Change the message for E226 to make clear that it is about arithmetic operators.

• Fix a false positive E128 for continuation line indentation with tabs.

• Fix regression with the --diff option. (Issue #169)

• Fix the TestReport class to print the unexpected warnings and errors.

1.4.3 (2013-02-22)

• Hide the --doctest and --testsuite options when installed.

• Fix crash with AST checkers when the syntax is invalid. (Issue #160)

• Read from standard input if no path is specified.

• Initiate a graceful shutdown on Control+C.

• Allow changing the checker_class for the StyleGuide.

1.4.2 (2013-02-10)

• Support AST checkers provided by third-party applications.

• Register new checkers with register_check(func_or_cls, codes).

• Allow constructing a StyleGuide with a custom parser.

• Accept visual indentation without parenthesis after the if statement. (Issue #151)

• Fix UnboundLocalError when using # noqa with continued lines. (Issue #158)

• Re-order the lines for the StandardReport.

• Expand tabs when checking E12 continuation lines. (Issue #155)

• Refactor the testing class TestReport and the specific test functions into a separate test module.

1.4.1 (2013-01-18)

• Allow sphinx.ext.autodoc syntax for comments. (Issue #110)

• Report E703 instead of E702 for the trailing semicolon. (Issue #117)

• Honor # noqa in addition to # nopep8. (Issue #149)

• Expose the OptionParser factory for better extensibility.

1.4 (2012-12-22)

• Report E226 instead of E225 for optional whitespace around common operators (*, **, /, + and -). This new error code is ignored in the default configuration because PEP 8 recommends to “use your own judgement”. (Issue #96)

• Lines with a # nopep8 at the end will not issue errors on line length E501 or continuation line indentation E12*. (Issue #27)

• Fix AssertionError when the source file contains an invalid line ending "\r\r\n". (Issue #119)

• Read the [pep8] section of tox.ini or setup.cfg if present. (Issue #93 and #141)

• Add the Sphinx-based documentation, and publish it on https://pycodestyle.readthedocs.io/. (Issue #105)

1.3.4 (2012-12-18)

• Fix false positive E124 and E128 with comments. (Issue #100)

• Fix error on stdin when running with bpython. (Issue #101)

• Fix false positive E401. (Issue #104)

• Report E231 for nested dictionary in list. (Issue #142)

• Catch E271 at the beginning of the line. (Issue #133)

• Fix false positive E126 for multi-line comments. (Issue #138)

• Fix false positive E221 when operator is preceded by a comma. (Issue #135)

• Fix --diff failing on one-line hunk. (Issue #137)

• Fix the --exclude switch for directory paths. (Issue #111)

• Use - filename to read from standard input. (Issue #128)

1.3.3 (2012-06-27)

• Fix regression with continuation line checker. (Issue #98)

1.3.2 (2012-06-26)

• Revert to the previous behaviour for --show-pep8: do not imply --first. (Issue #89)

• Add E902 for IO errors. (Issue #87)

• Fix false positive for E121, and missed E124. (Issue #92)

• Set a sensible default path for config file on Windows. (Issue #95)

• Allow verbose in the configuration file. (Issue #91)

• Show the enforced max-line-length in the error message. (Issue #86)

1.3.1 (2012-06-18)

• Explain which configuration options are expected. Accept and recommend the options names with hyphen instead of underscore. (Issue #82)

• Do not read the user configuration when used as a module (except if config_file=True is passed to the StyleGuide constructor).

• Fix wrong or missing cases for the E12 series.

• Fix cases where E122 was missed. (Issue #81)

1.3 (2012-06-15)

• Remove global configuration and refactor the library around a StyleGuide class; add the ability to configure various reporters. (Issue #35 and #66)

• Read user configuration from ~/.config/pep8 and local configuration from ./.pep8. (Issue #22)

• Fix E502 for backslash embedded in multi-line string. (Issue #68)

• Fix E225 for Python 3 iterable unpacking (PEP 3132). (Issue #72)

• Enable the new checkers from the E12 series in the default configuration.

• Suggest less error-prone alternatives for E712 errors.

• Rewrite checkers to run faster (E22, E251, E27).

• Fixed a crash when parsed code is invalid (too many closing brackets).

• Fix E127 and E128 for continuation line indentation. (Issue #74)

• New option --format to customize the error format. (Issue #23)

• New option --diff to check only modified code. The unified diff is read from STDIN. Example: hg diff | pep8 --diff (Issue #39)

• Correctly report the count of failures and set the exit code to 1 when the --doctest or the --testsuite fails.

• Correctly detect the encoding in Python 3. (Issue #69)

• Drop support for Python 2.3, 2.4 and 3.0. (Issue #78)

1.2 (2012-06-01)

• Add E121 through E128 for continuation line indentation. These checks are disabled by default. If you want to force all checks, use switch --select=E,W. Patch by Sam Vilain. (Issue #64)

• Add E721 for direct type comparisons. (Issue #47)

• Add E711 and E712 for comparisons to singletons. (Issue #46)

• Fix spurious E225 and E701 for function annotations. (Issue #29)

• Add E502 for explicit line join between brackets.

• Fix E901 when printing source with --show-source.

• Report all errors for each checker, instead of reporting only the first occurrence for each line.

• Option --show-pep8 implies --first.

1.1 (2012-05-24)

• Add E901 for syntax errors. (Issues #63 and #30)

• Add E271, E272, E273 and E274 for extraneous whitespace around keywords. (Issue #57)

• Add tox.ini configuration file for tests. (Issue #61)

• Add .travis.yml configuration file for continuous integration. (Issue #62)

1.0.1 (2012-04-06)

• Fix inconsistent version numbers.

1.0 (2012-04-04)

• Fix W602 raise to handle multi-char names. (Issue #53)

0.7.0 (2012-03-26)

• Now --first prints only the first occurrence of each error. The --repeat flag becomes obsolete because it is the default behaviour. (Issue #6)

• Allow specifying --max-line-length. (Issue #36)

• Make the shebang more flexible. (Issue #26)

• Add testsuite to the bundle. (Issue #25)

• Fixes for Jython. (Issue #49)

• Add PyPI classifiers. (Issue #43)

• Fix the --exclude option. (Issue #48)

• Fix W602, accept raise with 3 arguments. (Issue #34)

• Correctly select all tests if DEFAULT_IGNORE == ''.

0.6.1 (2010-10-03)

• Fix inconsistent version numbers. (Issue #21)

0.6.0 (2010-09-19)

• Test suite reorganized and enhanced in order to check more failures with fewer test files. Read the run_tests docstring for details about the syntax.

• Fix E225: accept print >>sys.stderr, "..." syntax.

• Fix E501 for lines containing multibyte encoded characters. (Issue #7)

• Fix E221, E222, E223, E224 not detected in some cases. (Issue #16)

• Fix E211 to reject v = dic['a'] ['b']. (Issue #17)

• Exit code is always 1 if any error or warning is found. (Issue #10)

• --ignore checks are now really ignored, especially in conjunction with --count. (Issue #8)

• Blank lines with spaces yield W293 instead of W291: some developers want to ignore this warning and indent the blank lines to paste their code easily in the Python interpreter.

• Fix E301: do not require a blank line before an indented block. (Issue #14)

• Fix E203 to accept NumPy slice notation a[0, :]. (Issue #13)

• Performance improvements.

• Fix decoding and checking non-UTF8 files in Python 3.

• Fix E225: reject True+False when running on Python 3.

• Fix an exception when the line starts with an operator.

• Allow a new line before closing ), } or ]. (Issue #5)

0.5.0 (2010-02-17)

• Changed the --count switch to print to sys.stderr and set exit code to 1 if any error or warning is found.

• E241 and E242 are removed from the standard checks. If you want to include these checks, use switch --select=E,W. (Issue #4)

• Blank line is not mandatory before the first class method or nested function definition, even if there’s a docstring. (Issue #1)

• Add the switch --version.

• Fix decoding errors with Python 3. (Issue #13 [1])

• Add --select option which is mirror of --ignore.

• Add checks E261 and E262 for spaces before inline comments.

• New check W604 warns about deprecated usage of backticks.

• New check W603 warns about the deprecated operator <>.

• Performance improvement, due to rewriting of E225.

• E225 now accepts:

  • no whitespace after unary operator or similar. (Issue #9 [1])

  • lambda function with argument unpacking or keyword defaults.

• Reserve “2 blank lines” for module-level logical blocks. (E303)

• Allow multi-line comments. (E302, issue #10 [1])

0.4.2 (2009-10-22)

• Decorators on classes and class methods are OK now.

0.4 (2009-10-20)

• Support for all versions of Python from 2.3 to 3.1.

• New and greatly expanded self tests.

• Added --count option to print the total number of errors and warnings.

• Further improvements to the handling of comments and blank lines. (Issue #1 [1] and others changes.)

• Check all py files in directory when passed a directory (Issue #2 [1]). This also prevents an exception when traversing directories with non *.py files.

• E231 should allow commas to be followed by ). (Issue #3 [1])

• Spaces are no longer required around the equals sign for keyword arguments or default parameter values.

0.3.1 (2009-09-14)

• Fixes for comments: do not count them when checking for blank lines between items.

• Added setup.py for pypi upload and easy_installability.

0.2 (2007-10-16)

• Loads of fixes and improvements.

0.1 (2006-10-01)

• First release.