formatter prefers to break annotation over arguments list

[davidszotten]

input:

def foo(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa) -> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
    ...

black (better choice imo)

def foo(
    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
) -> aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa:
    ...

ruff

def foo(aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa) -> (
    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
):
    ...

[tylerlaprade]

I'm pretty sure Black is changing this in their next version. Try running Black with the --preview flag enabled.

[davidszotten]

i see the same behaviour even with --preview

(black, 23.7.0 (compiled: yes))

[MichaReiser]

This shouldn't be to hard to fix. The arguments group must enclose the arguments and the return type annotation. This will make the printer to expand from left to right (outer most before inner groups)

[tylerlaprade]

https://black.readthedocs.io/en/stable/the_black_code_style/future_style.html#improved-line-breaks

Ah, I see, I guess this only applies to assignment. I assumed it would be similar for function definitions.

[davidszotten]

This shouldn't be to hard to fix. The arguments group must enclose the arguments and the return type annotation. This will make the printer to expand from left to right (outer most before inner groups)

not sure i quote follow what you mean by "the arguments group". i tried wrapping

ruff/crates/ruff_python_formatter/src/statement/stmt_function_def.rs

Lines 84 to 86 in 1ac2699

	write!(f, [item.arguments().format()])?;
	if let Some(return_annotation) = item.returns() {

in a group but that didn't do the trick

[MichaReiser]

The formatting of arguments creates a group. We'll need to create that group on the function level instead so that it includes both the arguments and the returns, similar to Prettier

[davidszotten]

sorry i can't get it to work. might have to leave for someone else

[charliermarsh]

I'll give it a look.

[charliermarsh]

I don't quite understand how to make the composition work here given that parenthesized and related helpers all create groups. IIUC we'd need to somehow pass the returns to the Parameters formatter, and then change parenthesized to allow for content after the maybe-parenthesized nodes that's part of the same group?

[charliermarsh]

I will revisit this today.

[MichaReiser]

You probably need to pull in the relevant parts from parenthesized into the function formatting. It's different enough. We did that previously with other formatting too (I can't recall out of my head which formatting it was but it manually creates the groups and sets the node level)