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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


1.4.5 (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)


The internal API is backwards incompatible.

  • 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 occurence 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 occurence 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.
[1](1, 2, 3, 4, 5, 6) These issues refer to the previous issue tracker.

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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