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Python style guide checker

Project description

pep8 - Python style guide checker

pep8 is a tool to check your Python code against some of the style conventions in PEP 8.


  • 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 file for this purpose.

  • Comes with a comprehensive test suite.


You can install, upgrade, uninstall with these commands:

$ pip install pep8
$ pip install --upgrade pep8
$ pip uninstall pep8

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

Example usage and output

$ pep8 --first E401 multiple imports on one line E302 expected 2 blank lines, found 1 E301 expected 1 blank line, found 0 W602 deprecated form of raising exception E211 whitespace before '(' E201 whitespace after '{' E221 multiple spaces before operator W601 .has_key() is deprecated, use 'in'

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

$ pep8 --show-source --show-pep8 testsuite/
testsuite/ 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:

$ pep8 --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


1.7.1 (2017-10-22)


  • Prominently note via warning message that the tool is no longer released as pep8 and will only be fixed in the pycodestyle package

1.7.0 (2016-01-12)



  • 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)


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

1.6.2 (2015-02-15)


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


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

1.6.1 (2015-02-08)


  • Assign variables before referenced. (Issue #287)


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

1.6.0 (2015-02-06)



  • 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: 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)


  • 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)


  • 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)


  • 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 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 to change 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 to construct 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 (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 to specify --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 for pypi upload and easy_installability.

0.2 (2007-10-16)

  • Loads of fixes and improvements.

0.1 (2006-10-01)

  • First release.

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