yapf: Line breaking behavior for function arguments with and without trailing comma

Hello! I have been evaluating bringing in yapf to a few projects. I found this thread and realized that the this issue applies to my current adoption. Has there been any resolutions, updates, or work-arounds discovered?

Maybe there was a misunderstanding what behavior we would like a trailing comma to cause. If there is a trailing comma, each argument and the closing parenthesis should have their own lines to easily edit individual arguments (regardless of line length and DEDENT_CLOSING_BRACKETS knob). Some examples to illustrate:

function_name(argument_name_1=1, argument_name_2=2, argument_name_3=3)

# Break even though this would fit into a single line.
function_name(
    argument_name_1=1,
    argument_name_2=2,
    argument_name_3=3,
)

a_very_long_function_name(
    long_argument_name_1=1, long_argument_name_2=2, long_argument_name_3=3,
    long_argument_name_4=4)

a_very_long_function_name(
    long_argument_name_1=1,
    long_argument_name_2=2,
    long_argument_name_3=3,
    long_argument_name_4=4,
)

What may help you get further towards the desired output is specifying SPLIT_BEFORE_NAMED_ASSIGNS: False. When I add that, it gives this:

$ python -m yapf --style='{based_on_style: pep8; SPLIT_BEFORE_NAMED_ASSIGNS: False}' /tmp/x.py
a_very_long_function_name(long_argument_name_1=1,
                          long_argument_name_2=2,
                          long_argument_name_3=3,
                          long_argument_name_4=4, )

a_very_long_function_name(long_argument_name_1=1, long_argument_name_2=2,
                          long_argument_name_3=3, long_argument_name_4=4)

There is another option you can set that can get you further:

$ python -m yapf --style='{based_on_style: pep8; SPLIT_BEFORE_NAMED_ASSIGNS: False, DEDENT_CLOSING_BRACKETS: True}' /tmp/x.py
a_very_long_function_name(
    long_argument_name_1=1,
    long_argument_name_2=2,
    long_argument_name_3=3,
    long_argument_name_4=4,
)

a_very_long_function_name(
    long_argument_name_1=1, long_argument_name_2=2, long_argument_name_3=3,
    long_argument_name_4=4
)

Please let me know if that works for you.

Okay. I added a new knob SPLIT_ARGUMENTS_WHEN_COMMA_TERMINATED which should do what you want. Please try it out on top-of-tree.

What are the current recommended knob settings for as little line breaking as possible (in function definitions and in function calls)?

So with this yapf config:

[style]
based_on_style = pep8
column_limit = 120
dedent_closing_brackets = true
join_multiple_lines = false
space_between_ending_comma_and_closing_bracket = false
split_arguments_when_comma_terminated = true

I now get this:

     class Meta:
-        unique_together = (
-            ("user", "issue"),
-            ("user", "company"),
-        )
+        unique_together = (("user", "issue"),
+                           ("user", "company"),)

But also this:

-        self.assertQuerysetEqual(issues, map(repr, [issue1, issue2]), ordered=False)
+        self.assertQuerysetEqual(issues, map(repr,
+                                             [
+                                                 issue1,
+                                                 issue2
+                                             ]), ordered=False)

Both suggestions are kind of odd. I would expect both examples to stay as is, unless they are over the line length limit. But maybe we have a very particular in-house style. Thanks for the updates!

Is this issue solved/feature implemented?