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Flake8 lint for trailing commas.

Project description

No Maintenance Intended

Note: Black, the uncompromising Python code formatter, or add-trailing-comma can do all this comma insertion automatically. We recommend you use one of those tools instead.


If you are using flake8 it’s as easy as:

pip install flake8-commas

Now you can avoid those annoying merge conflicts on dictionary and list diffs.


Different versions of python require commas in different places. Ignore the errors for languages you don’t use in your flake8 config:




missing trailing comma


missing trailing comma in Python 3


missing trailing comma in Python 2


missing trailing comma in Python 3.5+


missing trailing comma in Python 3.6+


trailing comma on bare tuple prohibited


trailing comma prohibited


lookup_table = {
    'key1': 'value',
    'key2': 'something'  # <-- missing a trailing comma

json_data = json.dumps({
    "key": "value",
}),                      # <-- incorrect trailing comma. json_data is now a tuple. Likely by accident.

2.1.0 (2021-10-13)

2.0.0 (2018-03-19)

1.0.0 (2018-01-04)

  • No changes from 0.5.1, just releasing the first major version.

0.5.1 (2018-01-02)

  • Refactor single/multi tuple/subscript to simply count commas in all cases.

  • Prohibit trailing commas in lambda parameter lists.

  • Fix a missing trailing comma false positive in subcripts with slices.

  • Fix a prohibited trailing comma false positve in subscripts with slices.

  • All (Issue #48)

0.5.0 (2018-01-02)

  • Remove EOL Python 3.3. (Issue #47)

  • Prohibit trailing commas where there is no following new line (or forming a single element tuple). (Issue #46)

0.4.3 (2017-04-25)

  • Enforce trailing commas in subscript tuples and slices again. Regression from 0.4.2 (Issue #42)

0.4.2 (2017-04-18)

  • Prevent lambda params in a parenth form enforcing a trailing comma. (Issue #41)

  • Fix issue preventing execution on Python 2 with Flake8 3. (Issue #35)

  • Allow bare wrapped subscript notation access. (Issue #39)

  • Don’t require comma in assert statement with parenth form. (Issue #37)

0.4.1 (2017-01-18)

  • Add the framework flake8 trove classifier.

0.4.0 (2017-01-18)

  • Support flake8 3.x.x. (Issue #20)

  • No trailing comma after any function def with unpack.

  • support Python 3.6 issue9232 trailing commas. (Issue #33)

0.3.1 (2017-01-18)

  • Also parse unpacks with literals. (Issue #30)

0.3.0 (2017-01-16)

  • If there is a comment after the last item, do not report an error. (Issue #18)

  • If there is an empty, tuple, list, dict, or function, do not report an error. (Issue #17)

  • Support PEP 3132 Python 3.5+ extended unpacking. (Issue #26)

  • *args should not require a trailing comma. (Issue #27)

0.2.0 (2017-01-13)

  • First version of flake8-commas with changelog

  • Fix HTML readme render on PyPI.

  • Support various parenth_form edge cases.

  • Merge from flake8-trailing-commas

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