0bec5c0362
Summary
--
This PR makes two changes to comment placement in lambda parameters.
First, we
now insert a line break if the first parameter has a leading comment:
```py
# input
(
lambda
* # comment 2
x:
x
)
# main
(
lambda # comment 2
*x: x
)
# this PR
(
lambda
# comment 2
*x: x
)
```
Note the missing space in the output from main. This case is currently
unstable
on main. Also note that the new formatting is more consistent with our
stable
formatting in cases where the lambda has its own dangling comment:
```py
# input
(
lambda # comment 1
* # comment 2
x:
x
)
# output
(
lambda # comment 1
# comment 2
*x: x
)
```
and when a parameter without a comment precedes the split `*x`:
```py
# input
(
lambda y,
* # comment 2
x:
x
)
# output
(
lambda y,
# comment 2
*x: x
)
```
This does change the stable formatting, but I think such cases are rare
(expecting zero hits in the ecosystem report), this fixes an existing
instability, and it should not change any code we've previously
formatted.
Second, this PR modifies the comment placement such that `# comment 2`
in these
outputs is still a leading comment on the parameter. This is also not
the case
on main, where it becomes a [dangling lambda
comment](https://play.ruff.rs/3b29bb7e-70e4-4365-88e0-e60fe1857a35?secondary=Comments).
This doesn't cause any
instability that I'm aware of on main, but it does cause problems when
trying to
adjust the placement of dangling lambda comments in #21385. Changing the
placement in this way should not affect any formatting here.
Test Plan
--
New lambda tests, plus existing tests covering the cases above with
multiple
comments around the parameters (see lambda.py 122-143, and 122-205 or so
more
broadly)
I also checked manually that the comments are now leading on the
parameter:
```shell
❯ cargo run --bin ruff_python_formatter -- --emit stdout --target-version 3.10 --print-comments <<EOF
(
lambda
# comment 2
*x: x
)
EOF
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.15s
Running `target/debug/ruff_python_formatter --emit stdout --target-version 3.10 --print-comments`
# Comment decoration: Range, Preceding, Following, Enclosing, Comment
21..32, None, Some((Parameters, 37..39)), (ExprLambda, 6..42), "# comment 2"
{
Node {
kind: Parameter,
range: 37..39,
source: `*x`,
}: {
"leading": [
SourceComment {
text: "# comment 2",
position: OwnLine,
formatted: true,
},
],
"dangling": [],
"trailing": [],
},
}
(
lambda
# comment 2
*x: x
)
```
But I didn't see a great place to put a test like this. Is there
somewhere I can assert this comment placement since it doesn't affect
any formatting yet? Or is it okay to wait until we use this in #21385?
|
||
|---|---|---|
| .. | ||
| resources/test/fixtures | ||
| src | ||
| tests | ||
| CONTRIBUTING.md | ||
| Cargo.toml | ||
| README.md | ||
| generate.py | ||
| orphan_rules_in_the_formatter.svg | ||
README.md
Ruff Formatter
The Ruff formatter is an extremely fast Python code formatter that ships as part of the ruff
CLI.
Goals
The formatter is designed to be a drop-in replacement for Black, but with an excessive focus on performance and direct integration with Ruff.
Specifically, the formatter is intended to emit near-identical output when run over Black-formatted code. When run over extensive Black-formatted projects like Django and Zulip, > 99.9% of lines are formatted identically. When migrating an existing project from Black to Ruff, you should expect to see a few differences on the margins, but the vast majority of your code should be unchanged.
If you identify deviations in your project, spot-check them against the intentional deviations enumerated below, as well as the unintentional deviations filed in the issue tracker. If you've identified a new deviation, please file an issue.
When run over non-Black-formatted code, the formatter makes some different decisions than Black, and so more deviations should be expected, especially around the treatment of end-of-line comments. For details, see Style Guide.
Getting started
Head to The Ruff Formatter for usage instructions and a comparison to Black.