Skip to main content

Automatically add trailing commas to calls and literals

Project description

Build Status Azure DevOps coverage pre-commit.ci status

add-trailing-comma

A tool (and pre-commit hook) to automatically add trailing commas to calls and literals.

Installation

pip install add-trailing-comma

As a pre-commit hook

See pre-commit for instructions

Sample .pre-commit-config.yaml:

-   repo: https://github.com/asottile/add-trailing-comma
    rev: v2.3.0
    hooks:
    -   id: add-trailing-comma

multi-line method invocation style -- why?

# Sample of *ideal* syntax
function_call(
    argument,
    5 ** 5,
    kwarg=foo,
)
  • the initial paren is at the end of the line
  • each argument is indented one level further than the function name
  • the last parameter (unless the call contains an unpacking (*args / **kwargs)) has a trailing comma

This has the following benefits:

  • arbitrary indentation is avoided:

    # I hear you like 15 space indents
    # oh your function name changed? guess you get to reindent :)
    very_long_call(arg,
                   arg,
                   arg)
    
  • adding / removing a parameter preserves git blame and is a minimal diff:

     # with no trailing commas
     x(
    -    arg
    +    arg,
    +    arg2
     )
    
     # with trailing commas
     x(
         arg,
    +    arg2,
     )
    

Implemented features

trailing commas for function calls

 x(
     arg,
-    arg
+    arg,
 )

trailing commas for function calls with unpackings

If --py35-plus is passed, add-trailing-comma will also perform the following change:

 x(
-    *args
+    *args,
 )
 y(
-    **kwargs
+    **kwargs,
 )

Note that this would cause a SyntaxError in earlier python versions.

trailing commas for tuple / list / dict / set literals

 x = [
-    1, 2, 3
+    1, 2, 3,
 ]

trailing commas for function definitions

 def func(
         arg1,
-        arg2
+        arg2,
 ):
 async def func(
         arg1,
-        arg2
+        arg2,
 ):

trailing commas for function definitions with unpacking arguments

If --py36-plus is passed, add-trailing-comma will also perform the following change:

 def f(
-    *args
+    *args,
 ): pass


 def g(
-    **kwargs
+    **kwargs,
 ): pass


 def h(
-    *, kw=1
+    *, kw=1,
 ): pass

Note that this would cause a SyntaxError in earlier python versions.

trailing commas for from imports

 from os import (
     path,
-    makedirs
+    makedirs,
 )

trailing comma for class definitions

 class C(
     Base1,
-    Base2
+    Base2,
 ):
     pass

trailing comma for with statement

 with (
         open('f1', 'r') as f1,
-        open('f2', 'w') as f2
+        open('f2', 'w') as f2,
 ):
     pass

trailing comma for match statement

 match x:
     case A(
        1,
-       2
+       2,
     ):
        pass
     case (
        1,
-       2
+       2,
     ):
        pass
     case [
        1,
-       2
+       2,
     ]:
        pass
     case {
        'x': 1,
-       'y': 2
+       'y': 2,
     }:
        pass

unhug trailing paren

 x(
     arg1,
-    arg2)
+    arg2,
+)

unhug leading paren

-function_name(arg1,
-              arg2)
+function_name(
+    arg1,
+    arg2,
+)

match closing brace indentation

 x = [
     1,
     2,
     3,
-    ]
+]

remove unnecessary commas

yes yes, I realize the tool is called add-trailing-comma :laughing:

-[1, 2, 3,]
-[1, 2, 3, ]
+[1, 2, 3]
+[1, 2, 3]

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

add_trailing_comma-2.3.0.tar.gz (11.5 kB view hashes)

Uploaded Source

Built Distribution

add_trailing_comma-2.3.0-py2.py3-none-any.whl (15.1 kB view hashes)

Uploaded Python 2 Python 3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page