## Summary
_This is preview only feature and is available using the `--preview`
command-line flag._
With the implementation of [PEP 701] in Python 3.12, f-strings can now
be broken into multiple lines, can contain comments, and can re-use the
same quote character. Currently, no other Python formatter formats the
f-strings so there's some discussion which needs to happen in defining
the style used for f-string formatting. Relevant discussion:
https://github.com/astral-sh/ruff/discussions/9785
The goal for this PR is to add minimal support for f-string formatting.
This would be to format expression within the replacement field without
introducing any major style changes.
### Newlines
The heuristics for adding newline is similar to that of
[Prettier](https://prettier.io/docs/en/next/rationale.html#template-literals)
where the formatter would only split an expression in the replacement
field across multiple lines if there was already a line break within the
replacement field.
In other words, the formatter would not add any newlines unless they
were already present i.e., they were added by the user. This makes
breaking any expression inside an f-string optional and in control of
the user. For example,
```python
# We wouldn't break this
aaaaaaaaaaa = f"asaaaaaaaaaaaaaaaa { aaaaaaaaaaaa + bbbbbbbbbbbb + ccccccccccccccc } cccccccccc"
# But, we would break the following as there's already a newline
aaaaaaaaaaa = f"asaaaaaaaaaaaaaaaa {
aaaaaaaaaaaa + bbbbbbbbbbbb + ccccccccccccccc } cccccccccc"
```
If there are comments in any of the replacement field of the f-string,
then it will always be a multi-line f-string in which case the formatter
would prefer to break expressions i.e., introduce newlines. For example,
```python
x = f"{ # comment
a }"
```
### Quotes
The logic for formatting quotes remains unchanged. The existing logic is
used to determine the necessary quote char and is used accordingly.
Now, if the expression inside an f-string is itself a string like, then
we need to make sure to preserve the existing quote and not change it to
the preferred quote unless it's 3.12. For example,
```python
f"outer {'inner'} outer"
# For pre 3.12, preserve the single quote
f"outer {'inner'} outer"
# While for 3.12 and later, the quotes can be changed
f"outer {"inner"} outer"
```
But, for triple-quoted strings, we can re-use the same quote char unless
the inner string is itself a triple-quoted string.
```python
f"""outer {"inner"} outer""" # valid
f"""outer {'''inner'''} outer""" # preserve the single quote char for the inner string
```
### Debug expressions
If debug expressions are present in the replacement field of a f-string,
then the whitespace needs to be preserved as they will be rendered as it
is (for example, `f"{ x = }"`. If there are any nested f-strings, then
the whitespace in them needs to be preserved as well which means that
we'll stop formatting the f-string as soon as we encounter a debug
expression.
```python
f"outer { x = !s :.3f}"
# ^^
# We can remove these whitespaces
```
Now, the whitespace doesn't need to be preserved around conversion spec
and format specifiers, so we'll format them as usual but we won't be
formatting any nested f-string within the format specifier.
### Miscellaneous
- The
[`hug_parens_with_braces_and_square_brackets`](https://github.com/astral-sh/ruff/issues/8279)
preview style isn't implemented w.r.t. the f-string curly braces.
- The
[indentation](https://github.com/astral-sh/ruff/discussions/9785#discussioncomment-8470590)
is always relative to the f-string containing statement
## Test Plan
* Add new test cases
* Review existing snapshot changes
* Review the ecosystem changes
[PEP 701]: https://peps.python.org/pep-0701/
## Summary
This PR implements the `blank_line_after_nested_stub_class` preview
style in the formatter.
The logic is divided into 3 parts:
1. In between preceding and following nodes at top level and nested
suite
2. When there's a trailing comment after the class
3. When there is no following node from (1) which is the case when it's
the last or the only node in a suite
We handle (3) with `FormatLeadingAlternateBranchComments`.
## Test Plan
- Add new test cases and update existing snapshots
- Checked the `typeshed` diff
fixes: #8891
## Summary
This is similar to https://github.com/astral-sh/ruff/pull/8876, but more
limited in scope:
1. It only applies to `# fmt: skip` (like Black). Like `# isort: on`, `#
fmt: on` needs to be on its own line (still).
2. It only delimits on `#`, so you can do `# fmt: skip # noqa`, but not
`# fmt: skip - some other content` or `# fmt: skip; noqa`.
If we want to support the `;`-delimited version, we should revisit
later, since we don't support that in the linter (so `# fmt: skip; noqa`
wouldn't register a `noqa`).
Closes https://github.com/astral-sh/ruff/issues/8892.
## Summary
I always found it odd that we had to pass this in, since it's really
higher-level context for the error. The awkwardness is further evidenced
by the fact that we pass in fake values everywhere (even outside of
tests). The source path isn't actually used to display the error; it's
only accessed elsewhere to _re-display_ the error in certain cases. This
PR modifies to instead pass the path directly in those cases.
## Summary
Add new test cases for `with_item` and `match` sequence that demonstrate how long headers break.
Removes one use of `optional_parentheses` in a position where it is know that the parentheses always need to be added.
## Test Plan
cargo test
This fixes a bug where the current indent level was not calculated
correctly for doctests. Namely, it didn't account for the extra indent
level (in terms of ASCII spaces) used by by the PS1 (`>>> `) and PS2
(`... `) prompts. As a result, lines could extend up to 4 spaces beyond
the configured line length limit.
We fix that by passing the `CodeExampleKind` to the `format` routine
instead of just the code itself. In this way, `format` can query whether
there will be any extra indent added _after_ formatting the code and
take that into account for its line length setting.
We add a few regression tests, taken directly from @stinodego's
examples.
Fixes#9126
This PR does the plumbing to make a new formatting option,
`docstring-code-format`, available in the configuration for end users.
It is disabled by default (opt-in). It is opt-in at least initially to
reflect a conservative posture. The intent is to make it opt-out at some
point in the future.
This was split out from #8811 in order to make #8811 easier to merge.
Namely, once this is merged, docstring code snippet formatting will
become available to end users. (See comments below for how we arrived at
the name.)
Closes#7146
## Test Plan
Other than the standard test suite, I ran the formatter over the CPython
and polars projects to ensure both that the result looked sensible and
that tests still passed. At time of writing, one issue that currently
appears is that reformatting code snippets trips the long line lint:
1905886802
## Summary
This PR changes the internal `docstring-code-line-width` setting to
additionally accept a string value `dynamic`. When `dynamic` is set, the
line width is dynamically adjusted when reformatting code snippets in
docstrings based on the indent level of the docstring. The result is
that the reformatted lines from the code snippet should not exceed the
"global" line width configuration for the surrounding source.
This PR does not change the default behavior, although I suspect the
default should probably be `dynamic`.
## Test Plan
I added a new configuration to the existing docstring code tests and
also added a new set of tests dedicated to the new `dynamic` mode.
## Summary
This does the light plumbing necessary to add a new internal option that
permits setting the line width of code examples in docstrings. The plan
is to add the corresponding user facing knob in #8854.
Note that this effectively removes the `same-as-global` configuration
style discussed [in this
comment](https://github.com/astral-sh/ruff/issues/8855#issuecomment-1847230440).
It replaces it with the `{integer}` configuration style only.
There are a lot of commits here, but they are each tiny to make review
easier because of the changes to snapshots.
## Test Plan
I added a new docstring test configuration that sets
`docstring-code-line-width = 60` and examined the differences.
## Summary
In https://github.com/astral-sh/ruff/pull/8921, we changed our parameter
formatting behavior to add a trailing comma whenever a single-argument
function breaks. This introduced a deviation in the case that a function
contains a single argument, but _also_ includes a positional-only or
keyword-only separator.
Closes https://github.com/astral-sh/ruff/issues/9074.
(This is not possible to actually use until
https://github.com/astral-sh/ruff/pull/8854 is merged.)
This commit slots in support for formatting Markdown fenced code
blocks[1]. With the refactoring done for reStructuredText previously,
this ended up being pretty easy to add. Markdown code blocks are also
quite a bit easier to parse and recognize correctly.
One point of contention in #8860 is whether to assume that unlabeled
Markdown code fences are Python or not by default. In this PR, we make
such an assumption. This follows what `rustdoc` does. The mitigation
here is that if an unlabeled code block isn't Python, then it probably
won't parse as Python. And we'll end up skipping it. So in the vast
majority of cases, the worst thing that can happen is a little bit of
wasted work.
Closes#8860
[1]: https://spec.commonmark.org/0.30/#fenced-code-blocks
(This is not possible to actually use until
https://github.com/astral-sh/ruff/pull/8854 is merged.)
ruff_python_formatter: add reStructuredText docstring formatting support
This commit makes use of the refactoring done in prior commits to slot
in reStructuredText support. Essentially, we add a new type of code
example and look for *both* literal blocks and code block directives.
Literal blocks are treated as Python by default because it seems to be a
[common
practice](https://github.com/adamchainz/blacken-docs/issues/195).
That is, literal blocks like this:
```
def example():
"""
Here's an example::
foo( 1 )
All done.
"""
pass
```
Will get reformatted. And code blocks (via reStructuredText directives)
will also get reformatted:
```
def example():
"""
Here's an example:
.. code-block:: python
foo( 1 )
All done.
"""
pass
```
When looking for a code block, it is possible for it to become invalid.
In which case, we back out of looking for a code example and print the
lines out as they are. As with doctest formatting, if reformatting the
code would result in invalid Python or if the code collected from the
block is invalid, then formatting is also skipped.
A number of tests have been added to check both the formatting and
resetting behavior. Mixed indentation is also tested a fair bit, since
one of my initial attempts at dealing with mixed indentation ended up
not working.
I recommend working through this PR commit-by-commit. There is in
particular a somewhat gnarly refactoring before reST support is added.
Closes#8859
## Summary
We should avoid inlining the ellipsis in:
```python
def h():
...
# bye
```
Just as we omit the ellipsis in:
```python
def h():
# bye
...
```
Closes https://github.com/astral-sh/ruff/issues/8905.
In the source of working on #8859, I made a number of smallish refactors
to how code snippet formatting works. Most or all of these were
motivated by writing in support for reStructuredText blocks. They have
some fundamentally different requirements than doctests, and there are a
lot more ways for reStructuredText blocks to become invalid.
(Commit-by-commit review is recommended as the commit messages provide
further context on each change. I split this off from ongoing work to
make review more manageable.)
