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add-trailing-comma

library4.0.0pypypiunverified

add-trailing-comma is a Python utility that automatically adds trailing commas to function calls and literal structures (like lists, tuples, dictionaries, sets) to improve diff clarity and make future additions easier. It is currently at version 4.0.0 and is actively maintained, with releases often tied to Python version updates.

testing

pip install add-trailing-comma

github ↗package ↗

INSTALL

IMPORT

SIG · ADD-TRAILING-COMMA

add-trailing-comma

testingpythonv4.0.0

Install

1.6s avg

Import

—

Disk

16MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v4.0.0 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.910 runs

installs and imports cleanly · install 0.0s · import 0.000s · 18MB

glibc

py 3.10–3.910 runs

installs and imports cleanly · install 1.6s · import 0.000s · 18MB

16MB installed

● package 16MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

add-trailing-comma (CLI)

✓ add-trailing-comma <filenames>...

✗ import add_trailing_comma

This library is a command-line tool and is not intended for programmatic import or direct use as a Python module.

First, create a Python file with some function calls or literals. Then, run `add-trailing-comma` on that file from your terminal. The tool will modify the file in-place, adding trailing commas where applicable.

# Create a Python file, e.g., 'example.py' # -- example.py BEFORE -- # def my_function(arg1, arg2): # pass # # my_list = [ # 1, # 2 # ] # # my_dict = { # 'key1': 'value1', # 'key2': 'value2' # } # Run the tool from your terminal: # $ add-trailing-comma example.py # -- example.py AFTER -- # def my_function(arg1, arg2,): # pass # # my_list = [ # 1, # 2, # ] # # my_dict = { # 'key1': 'value1', # 'key2': 'value2', # }

add-trailing-comma --version

Debug

Known issues

breakingAs of version 4.0.0, the `add-trailing-comma` tool itself now requires Python 3.10 or newer to run. Attempting to install or execute it with older Python versions will result in an error.

fix

Ensure you are running `add-trailing-comma` within a Python 3.10+ environment. If you need to use an older Python environment, you must install an older version of `add-trailing-comma` (e.g., `<4.0.0`).

affects: 4.0.0+

breakingThe command-line flags `--py36-plus` and `--py310-plus` were removed in version 4.0.0. The tool now automatically infers the target Python version of the code it's formatting based on the Python environment it's running in.

fix

Remove these flags from your command-line invocations or pre-commit configurations. The tool will now handle the appropriate Python version inference.

affects: 4.0.0+

gotcha`add-trailing-comma` modifies files in-place without creating backups. It is strongly recommended to use this tool within a version-controlled repository (e.g., Git) to easily review and revert any unintended changes.

fix

Always commit your code before running `add-trailing-comma` or ensure you have a robust backup strategy. Integrate it as part of a pre-commit hook for automated version control management.

affects: All versions

gotchaWhen combining `add-trailing-comma` with other code formatters (e.g., Black, Ruff), it should generally be run *before* the other formatters in your pipeline (e.g., pre-commit hooks). Some opinionated formatters might remove trailing commas in certain contexts, potentially undoing `add-trailing-comma`'s work if run out of order.

fix

Configure your pre-commit hooks or formatting scripts to execute `add-trailing-comma` before other formatters that might conflict with trailing comma placement.

affects: All versions

Upgrade

Version history

4.0.0latest on PyPI · released Oct 10, 2025

Audit

Dependencies

No dependency data recorded yet.

Agent activity

47 hits · last 30 days

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OpenAI (training)

Resources

githubhttps://github.com/asottile/add-trailing-comma ↗

packagehttps://pypi.org/project/add-trailing-comma/ ↗