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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.

Mailing List


  • 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:

$ sudo apt-get install pep8

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

Quick help is available on the command line:

$ pep8 -h
Usage: pep8 [options] input ...

  --version            show program's version number and exit
  -h, --help           show this help message and exit
  -v, --verbose        print status messages, or debug with -vv
  -q, --quiet          report only file names, or nothing with -qq
  -r, --repeat         (obsolete) show all occurrences of the same error
  --first              show first occurrence of each error
  --exclude=patterns   exclude files or directories which match these comma
                       separated patterns (default: .svn,CVS,.bzr,.hg,.git)
  --filename=patterns  when parsing directories, only check filenames matching
                       these comma separated patterns (default: *.py)
  --select=errors      select errors and warnings (e.g. E,W6)
  --ignore=errors      skip errors and warnings (e.g. E4,W)
  --show-source        show source code for each error
  --show-pep8          show text of PEP 8 for each error (implies --first)
  --statistics         count errors and warnings
  --count              print total number of errors and warnings to standard
                       error and set exit code to 1 if total is not null
  --max-line-length=n  set maximum allowed line length (default: 79)
  --format=format      set the error format [default|pylint|<custom>]
  --diff               report only lines changed according to the unified diff
                       received on STDIN

  Testing Options:
    --testsuite=dir    run regression tests from dir
    --doctest          run doctest on myself
    --benchmark        measure processing speed

    The project options are read from the [pep8] section of the .pep8 file
    located in any parent folder of the path(s) being processed. Allowed
    options are: exclude, filename, select, ignore, max-line-length,
    count, format, quiet, show-pep8, show-source, statistics, verbose.

    --config=path      config file location (default: /home/user/.config/pep8)


Your feedback is more than welcome. Write email to or post bugs and feature requests on github:

Source download

Build status

The source code is currently available on github. Fork away!


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 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.

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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