Flake8 Extension to enforce better comma placement.

|Build Status| |PyPI - Version|

Usage

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

.. code:: shell

pip install flake8-commas

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

Errors

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

+------+-----------------------------------------+
| Code | message |
+======+=========================================+
| C812 | missing trailing comma |
+------+-----------------------------------------+
| C813 | missing trailing comma in Python 3 |
+------+-----------------------------------------+
| C814 | missing trailing comma in Python 2 |
+------+-----------------------------------------+
| C815 | missing trailing comma in Python 3.5+ |
+------+-----------------------------------------+
| C816 | missing trailing comma in Python 3.6+ |
+------+-----------------------------------------+
| C818 | trailing comma on bare tuple prohibited |
+------+-----------------------------------------+
| C819 | trailing comma prohibited |
+------+-----------------------------------------+

Examples

.. code:: Python

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.

Related tools

You may wish to consider one of the following tools alongside or instead of flake8-commas.

For automatic insertion of commas, though noting that these tools may implement
different rules around where commas should be placed:

black <https://pypi.org/project/black/>_, the uncompromising Python code formatter
add-trailing-comma <https://github.com/asottile/add-trailing-comma>_, which can do comma insertion automatically

.. |Build Status| image:: https://github.com/PyCQA/flake8-commas/actions/workflows/.github/workflows/tests.yml/badge.svg?branch=main
:target: https://github.com/PyCQA/flake8-commas/actions?query=branch%3Amain

.. |PyPI - Version| image:: https://img.shields.io/pypi/v/flake8-commas
:target: https://pypi.org/project/flake8-commas/

4.0.0 (2024-05-16)

Project renamed back to flake8-commas. If upgrading from
flake8-commas-x you should uninstall that package before
installing this one as both packages install the same modules.

3.0.0 (2024-03-12)

Project renamed to flake8-commas-x to continue maintenance.
Support dropped for Python <3.8.
Support added for Python 3.12.
Drop explicit noqa handling; this is handled by flake8 now.
Remove use of pkg_resources in favour of importlib.
CI moved to GitHub Actions.

2.1.0 (2021-10-13)

Remove upper bound on flake8.
(Issue #67 <https://github.com/PyCQA/flake8-commas/issues/67>_)
Note: this project is no longer maintained, and now black
or https://github.com/asottile/add-trailing-comma is recommended instead.
(Issue #63 <https://github.com/PyCQA/flake8-commas/pull/63>)
(Issue #69 <https://github.com/PyCQA/flake8-commas/pull/69>)

2.0.0 (2018-03-19)

Hide .base from flake8 --version.
(Issue #45 <https://github.com/PyCQA/flake8-commas/issue/45>)
Update URL to https://github.com/PyCQA/flake8-commas/.
(Issue #51 <https://github.com/PyCQA/flake8-commas/pull/51>_)
Add check for trailing commas on bare tuples - C818, thanks to
Chris AtLee <https://github.com/catlee>_ and
Arkadiusz Adamski <https://github.com/ar4s/flake8_tuple>_
(PR #52 <https://github.com/PyCQA/flake8-commas/pull/52>_)

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 <https://github.com/flake8-commas/flake8-commas/pull/48>_)

0.5.0 (2018-01-02)

Remove EOL Python 3.3.
(Issue #47 <https://github.com/flake8-commas/flake8-commas/pull/47>_)
Prohibit trailing commas where there is no following new line
(or forming a single element tuple).
(Issue #46 <https://github.com/flake8-commas/flake8-commas/pull/46>_)

0.4.3 (2017-04-25)

Enforce trailing commas in subscript tuples and slices again.
Regression from 0.4.2
(Issue #42 <https://github.com/flake8-commas/flake8-commas/pull/42>_)

0.4.2 (2017-04-18)

Prevent lambda params in a parenth form enforcing a trailing comma.
(Issue #41 <https://github.com/flake8-commas/flake8-commas/pull/41>_)
Fix issue preventing execution on Python 2 with Flake8 3.
(Issue #35 <https://github.com/flake8-commas/flake8-commas/issues/35>_)
Allow bare wrapped subscript notation access.
(Issue #39 <https://github.com/flake8-commas/flake8-commas/pull/39>_)
Don't require comma in assert statement with parenth form.
(Issue #37 <https://github.com/flake8-commas/flake8-commas/pull/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 <https://github.com/flake8-commas/flake8-commas/issue/20>_)
No trailing comma after any function def with unpack.
support Python 3.6 issue9232 <https://bugs.python.org/issue9232>_
trailing commas.
(Issue #33 <https://github.com/flake8-commas/flake8-commas/pull/33>_)

0.3.1 (2017-01-18)

Also parse unpacks with literals.
(Issue #30 <https://github.com/flake8-commas/flake8-commas/issue/30>_)

0.3.0 (2017-01-16)

If there is a comment after the last item, do not report an error.
(Issue #18 <https://github.com/flake8-commas/flake8-commas/issue/18>_)
If there is an empty, tuple, list, dict, or function, do not report an error.
(Issue #17 <https://github.com/flake8-commas/flake8-commas/issue/17>_)
Support PEP 3132 Python 3.5+ extended unpacking.
(Issue #26 <https://github.com/flake8-commas/flake8-commas/issue/26>_)
*args should not require a trailing comma.
(Issue #27 <https://github.com/flake8-commas/flake8-commas/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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