d9e59b21cd
## Summary
Black supports for layouts when it comes to breaking binary expressions:
```rust
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
enum BinaryLayout {
/// Put each operand on their own line if either side expands
Default,
/// Try to expand the left to make it fit. Add parentheses if the left or right don't fit.
///
///```python
/// [
/// a,
/// b
/// ] & c
///```
ExpandLeft,
/// Try to expand the right to make it fix. Add parentheses if the left or right don't fit.
///
/// ```python
/// a & [
/// b,
/// c
/// ]
/// ```
ExpandRight,
/// Both the left and right side can be expanded. Try in the following order:
/// * expand the right side
/// * expand the left side
/// * expand both sides
///
/// to make the expression fit
///
/// ```python
/// [
/// a,
/// b
/// ] & [
/// c,
/// d
/// ]
/// ```
ExpandRightThenLeft,
}
```
Our current implementation only handles `ExpandRight` and `Default` correctly. `ExpandLeft` turns out to be surprisingly hard. This PR adds a new `BestFittingMode` parameter to `BestFitting` to support `ExpandLeft`.
There are 3 variants that `ExpandLeft` must support:
**Variant 1**: Everything fits on the line (easy)
```python
[a, b] + c
```
**Variant 2**: Left breaks, but right fits on the line. Doesn't need parentheses
```python
[
a,
b
] + c
```
**Variant 3**: The left breaks, but there's still not enough space for the right hand side. Parenthesize the whole expression:
```python
(
[
a,
b
]
+ ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc
)
```
Solving Variant 1 and 2 on their own is straightforward The printer gives us this behavior by nesting right inside of the group of left:
```
group(&format_args![
if_group_breaks(&text("(")),
soft_block_indent(&group(&format_args![
left,
soft_line_break_or_space(),
op,
space(),
group(&right)
])),
if_group_breaks(&text(")"))
])
```
The fundamental problem is that the outer group, which adds the parentheses, always breaks if the left side breaks. That means, we end up with
```python
(
[
a,
b
] + c
)
```
which is not what we want (we only want parentheses if the right side doesn't fit).
Okay, so nesting groups don't work because of the outer parentheses. Sequencing groups doesn't work because it results in a right-to-left breaking which is the opposite of what we want.
Could we use best fitting? Almost!
```
best_fitting![
// All flat
format_args![left, space(), op, space(), right],
// Break left
format_args!(group(&left).should_expand(true), space(), op, space(), right],
// Break all
format_args![
text("("),
block_indent!(&format_args![
left,
hard_line_break(),
op,
space()
right
])
]
]
```
I hope I managed to write this up correctly. The problem is that the printer never reaches the 3rd variant because the second variant always fits:
* The `group(&left).should_expand(true)` changes the group so that all `soft_line_breaks` are turned into hard line breaks. This is necessary because we want to test if the content fits if we break after the `[`.
* Now, the whole idea of `best_fitting` is that you can pretend that some content fits on the line when it actually does not. The way this works is that the printer **only** tests if all the content of the variant **up to** the first line break fits on the line (we insert that line break by using `should_expand(true))`. The printer doesn't care whether the rest `a\n, b\n ] + c` all fits on (multiple?) lines.
Why does breaking right work but not breaking the left? The difference is that we can make the decision whether to parenthesis the expression based on the left expression. We can't do this for breaking left because the decision whether to insert parentheses or not would depend on a lookahead: will the right side break. We simply don't know this yet when printing the parentheses (it would work for the right parentheses but not for the left and indent).
What we kind of want here is to tell the printer: Look, what comes here may or may not fit on a single line but we don't care. Simply test that what comes **after** fits on a line.
This PR adds a new `BestFittingMode` that has a new `AllLines` option that gives us the desired behavior of testing all content and not just up to the first line break.
## Test Plan
I added a new example to `BestFitting::with_mode`
Ruff
Discord | Docs | Playground
An extremely fast Python linter, written in Rust.
Linting the CPython codebase from scratch.
- ⚡️ 10-100x faster than existing linters
- 🐍 Installable via
pip - 🛠️
pyproject.tomlsupport - 🤝 Python 3.11 compatibility
- 📦 Built-in caching, to avoid re-analyzing unchanged files
- 🔧 Autofix support, for automatic error correction (e.g., automatically remove unused imports)
- 📏 Over 500 built-in rules
- ⚖️ Near-parity with the built-in Flake8 rule set
- 🔌 Native re-implementations of dozens of Flake8 plugins, like flake8-bugbear
- ⌨️ First-party editor integrations for VS Code and more
- 🌎 Monorepo-friendly, with hierarchical and cascading configuration
Ruff aims to be orders of magnitude faster than alternative tools while integrating more functionality behind a single, common interface.
Ruff can be used to replace Flake8 (plus dozens of plugins), isort, pydocstyle, yesqa, eradicate, pyupgrade, and autoflake, all while executing tens or hundreds of times faster than any individual tool.
Ruff is extremely actively developed and used in major open-source projects like:
...and many more.
Ruff is backed by Astral. Read the launch post, or the original project announcement.
Testimonials
Sebastián Ramírez, creator of FastAPI:
Ruff is so fast that sometimes I add an intentional bug in the code just to confirm it's actually running and checking the code.
Nick Schrock, founder of Elementl, co-creator of GraphQL:
Why is Ruff a gamechanger? Primarily because it is nearly 1000x faster. Literally. Not a typo. On our largest module (dagster itself, 250k LOC) pylint takes about 2.5 minutes, parallelized across 4 cores on my M1. Running ruff against our entire codebase takes .4 seconds.
Bryan Van de Ven, co-creator of Bokeh, original author of Conda:
Ruff is ~150-200x faster than flake8 on my machine, scanning the whole repo takes ~0.2s instead of ~20s. This is an enormous quality of life improvement for local dev. It's fast enough that I added it as an actual commit hook, which is terrific.
Timothy Crosley, creator of isort:
Just switched my first project to Ruff. Only one downside so far: it's so fast I couldn't believe it was working till I intentionally introduced some errors.
Tim Abbott, lead developer of Zulip:
This is just ridiculously fast...
ruffis amazing.
Table of Contents
For more, see the documentation.
Getting Started
For more, see the documentation.
Installation
Ruff is available as ruff on PyPI:
pip install ruff
You can also install Ruff via Homebrew, Conda, and with a variety of other package managers.
Usage
To run Ruff, try any of the following:
ruff check . # Lint all files in the current directory (and any subdirectories)
ruff check path/to/code/ # Lint all files in `/path/to/code` (and any subdirectories)
ruff check path/to/code/*.py # Lint all `.py` files in `/path/to/code`
ruff check path/to/code/to/file.py # Lint `file.py`
Ruff can also be used as a pre-commit hook:
- repo: https://github.com/astral-sh/ruff-pre-commit
# Ruff version.
rev: v0.0.272
hooks:
- id: ruff
Ruff can also be used as a VS Code extension or alongside any other editor through the Ruff LSP.
Ruff can also be used as a GitHub Action via
ruff-action:
name: Ruff
on: [ push, pull_request ]
jobs:
ruff:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
- uses: chartboost/ruff-action@v1
Configuration
Ruff can be configured through a pyproject.toml, ruff.toml, or .ruff.toml file (see:
Configuration, or Settings
for a complete list of all configuration options).
If left unspecified, the default configuration is equivalent to:
[tool.ruff]
# Enable pycodestyle (`E`) and Pyflakes (`F`) codes by default.
select = ["E", "F"]
ignore = []
# Allow autofix for all enabled rules (when `--fix`) is provided.
fixable = ["A", "B", "C", "D", "E", "F", "G", "I", "N", "Q", "S", "T", "W", "ANN", "ARG", "BLE", "COM", "DJ", "DTZ", "EM", "ERA", "EXE", "FBT", "ICN", "INP", "ISC", "NPY", "PD", "PGH", "PIE", "PL", "PT", "PTH", "PYI", "RET", "RSE", "RUF", "SIM", "SLF", "TCH", "TID", "TRY", "UP", "YTT"]
unfixable = []
# Exclude a variety of commonly ignored directories.
exclude = [
".bzr",
".direnv",
".eggs",
".git",
".git-rewrite",
".hg",
".mypy_cache",
".nox",
".pants.d",
".pytype",
".ruff_cache",
".svn",
".tox",
".venv",
"__pypackages__",
"_build",
"buck-out",
"build",
"dist",
"node_modules",
"venv",
]
# Same as Black.
line-length = 88
# Allow unused variables when underscore-prefixed.
dummy-variable-rgx = "^(_+|(_+[a-zA-Z0-9_]*[a-zA-Z0-9]+?))$"
# Assume Python 3.10.
target-version = "py310"
[tool.ruff.mccabe]
# Unlike Flake8, default to a complexity level of 10.
max-complexity = 10
Some configuration options can be provided via the command-line, such as those related to rule enablement and disablement, file discovery, logging level, and more:
ruff check path/to/code/ --select F401 --select F403 --quiet
See ruff help for more on Ruff's top-level commands, or ruff help check for more on the
linting command.
Rules
Ruff supports over 500 lint rules, many of which are inspired by popular tools like Flake8, isort, pyupgrade, and others. Regardless of the rule's origin, Ruff re-implements every rule in Rust as a first-party feature.
By default, Ruff enables Flake8's E and F rules. Ruff supports all rules from the F category,
and a subset of the E category, omitting those
stylistic rules made obsolete by the use of an autoformatter, like
Black.
If you're just getting started with Ruff, the default rule set is a great place to start: it catches a wide variety of common errors (like unused imports) with zero configuration.
Beyond the defaults, Ruff re-implements some of the most popular Flake8 plugins and related code quality tools, including:
- autoflake
- eradicate
- flake8-2020
- flake8-annotations
- flake8-async
- flake8-bandit (#1646)
- flake8-blind-except
- flake8-boolean-trap
- flake8-bugbear
- flake8-builtins
- flake8-commas
- flake8-comprehensions
- flake8-copyright
- flake8-datetimez
- flake8-debugger
- flake8-django
- flake8-docstrings
- flake8-eradicate
- flake8-errmsg
- flake8-executable
- flake8-future-annotations
- flake8-gettext
- flake8-implicit-str-concat
- flake8-import-conventions
- flake8-logging-format
- flake8-no-pep420
- flake8-pie
- flake8-print
- flake8-pyi
- flake8-pytest-style
- flake8-quotes
- flake8-raise
- flake8-return
- flake8-self
- flake8-simplify
- flake8-slots
- flake8-super
- flake8-tidy-imports
- flake8-todos
- flake8-type-checking
- flake8-use-pathlib
- flynt (#2102)
- isort
- mccabe
- pandas-vet
- pep8-naming
- pydocstyle
- pygrep-hooks
- pylint-airflow
- pyupgrade
- tryceratops
- yesqa
For a complete enumeration of the supported rules, see Rules.
Contributing
Contributions are welcome and highly appreciated. To get started, check out the contributing guidelines.
You can also join us on Discord.
Support
Having trouble? Check out the existing issues on GitHub, or feel free to open a new one.
You can also ask for help on Discord.
Acknowledgements
Ruff's linter draws on both the APIs and implementation details of many other tools in the Python ecosystem, especially Flake8, Pyflakes, pycodestyle, pydocstyle, pyupgrade, and isort.
In some cases, Ruff includes a "direct" Rust port of the corresponding tool. We're grateful to the maintainers of these tools for their work, and for all the value they've provided to the Python community.
Ruff's autoformatter is built on a fork of Rome's rome_formatter,
and again draws on both the APIs and implementation details of Rome,
Prettier, and Black.
Ruff is also influenced by a number of tools outside the Python ecosystem, like Clippy and ESLint.
Ruff is the beneficiary of a large number of contributors.
Ruff is released under the MIT license.
Who's Using Ruff?
Ruff is used by a number of major open-source projects and companies, including:
- Amazon (AWS SAM)
- Apache Airflow
- AstraZeneca (Magnus)
- Benchling (Refac)
- Babel
- Bokeh
- Cryptography (PyCA)
- DVC
- Dagger
- Dagster
- FastAPI
- Gradio
- Great Expectations
- Hugging Face (Transformers, Datasets, Diffusers)
- Hatch
- Home Assistant
- Ibis
- Jupyter
- LangChain
- LlamaIndex
- Matrix (Synapse)
- Meltano (Meltano CLI, Singer SDK)
- Modern Treasury (Python SDK)
- Mozilla (Firefox)
- MegaLinter
- Microsoft (Semantic Kernel, ONNX Runtime, LightGBM)
- Netflix (Dispatch)
- Neon
- ONNX
- OpenBB
- PDM
- PaddlePaddle
- Pandas
- Poetry
- Polars
- PostHog
- Prefect (Python SDK, Marvin)
- PyInstaller
- PyTorch
- Pydantic
- Pylint
- Pynecone
- Robyn
- Scale AI (Launch SDK)
- Snowflake (SnowCLI)
- Saleor
- SciPy
- Sphinx
- Stable Baselines3
- Litestar
- The Algorithms
- Vega-Altair
- WordPress (Openverse)
- ZenML
- Zulip
- build (PyPA)
- cibuildwheel (PyPA)
- delta-rs
- featuretools
- meson-python
- nox
Show Your Support
If you're using Ruff, consider adding the Ruff badge to project's README.md:
[](https://github.com/astral-sh/ruff)
...or README.rst:
.. image:: https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/charliermarsh/ruff/main/assets/badge/v2.json
:target: https://github.com/astral-sh/ruff
:alt: Ruff
...or, as HTML:
<a href="https://github.com/astral-sh/ruff"><img src="https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/charliermarsh/ruff/main/assets/badge/v2.json" alt="Ruff" style="max-width:100%;"></a>
License
MIT
