Formatter: deviation from black: dict key split to multiline

[minusf]

ruff 0.4.8 python 3.10.14 macos 14.5

[tool.ruff]
line-length = 100

input:

        self.fields["redirect_link"].help_text = "Please do not use Tiny URLs for links to other www.xxxx.xxx pages."

black==24.4.2:

        self.fields["redirect_link"].help_text = (
            "Please do not use Tiny URLs for links to other www.xxxx.xxx pages."
        )

ruff==0.4.8

        self.fields[
            "redirect_link"
        ].help_text = "Please do not use Tiny URLs for links to other www.xxx.xxx pages."

[minusf]

I couldn't find this one on the list of known deviations, and this was quite disliked with black IIRC.

[minusf]

also, ruff converted the black output (as well as the input) to the multiline version

[MichaReiser]

I can confirm that Ruff formats this differently than Black.

Black's behavior is more consistent here in that it always tries to break the right first, before breaking the left. Ruff tries to do the same but I think it doesn't because of BestFitParanthesize's semantic.

Ruff uses BestFitParenthesize for the right side, and the left uses regular groups. The default behavior of the Printer is to prefer breaking right over left, by only testing if what comes after a group contains a line break before exceeding the line width. The problem is, there is no line break according to our current implementation. There's an inline comment that I wrote... but I'm not sure I understand what I meant at that time.

ruff/crates/ruff_formatter/src/printer/mod.rs

Lines 1289 to 1291 in 5806bc9

	// Don't use the parenthesized with indent layout even when measuring expanded mode similar to `BestFitting`.
	// This is to expand the left and not right after the `(` parentheses (it is okay to expand after the content that it wraps).
	self.stack.push(TagKind::BestFitParenthesize, args);

Unfortunately, my hope that this would be fixed by #8940 is unjustified. This only changes another small difference.

I'll need to take a closer look at this. Ultimately, I think we can only release this in a new minor version because it will break existing formatting.

[minusf]

thank you for looking into this. maybe it's worth adding it to the list of known deviations? it is a quite common occurance...