-
-
+
+
@@ -27,21 +25,12 @@ becomes transparent after a while and you can focus on the content instead.
_Black_ makes code review faster by producing the smallest diffs possible.
-Try it out now using the [Black Playground](https://black.now.sh). Watch the
+Try it out now using the [Black Playground](https://black.vercel.app). Watch the
[PyCon 2019 talk](https://youtu.be/esZLCuWs_2Y) to learn more.
---
-_Contents:_ **[Installation and usage](#installation-and-usage)** |
-**[Code style](#the-black-code-style)** | **[Pragmatism](#pragmatism)** |
-**[pyproject.toml](#pyprojecttoml)** | **[Editor integration](#editor-integration)** |
-**[blackd](#blackd)** | **[black-primer](#black-primer)** |
-**[Version control integration](#version-control-integration)** |
-**[GitHub Actions](#github-actions)** |
-**[Ignoring unmodified files](#ignoring-unmodified-files)** | **[Used by](#used-by)** |
-**[Testimonials](#testimonials)** | **[Show your style](#show-your-style)** |
-**[Contributing](#contributing-to-black)** | **[Change log](#change-log)** |
-**[Authors](#authors)**
+**[Read the documentation on ReadTheDocs!](https://black.readthedocs.io/en/stable)**
---
@@ -49,15 +38,12 @@ _Contents:_ **[Installation and usage](#installation-and-usage)** |
### Installation
-_Black_ can be installed by running `pip install black`. It requires Python 3.6.2+ to
-run. If you want to format Python 2 code as well, install with
-`pip install black[python2]`.
-
-#### Install from GitHub
+_Black_ can be installed by running `pip install black`. It requires Python 3.7+ to run.
+If you want to format Jupyter Notebooks, install with `pip install "black[jupyter]"`.
If you can't wait for the latest _hotness_ and want to install from GitHub, use:
-`pip install git+git://github.com/psf/black`
+`pip install git+https://github.com/psf/black`
### Usage
@@ -73,402 +59,98 @@ You can run _Black_ as a package if running it as a script doesn't work:
python -m black {source_file_or_directory}
```
-### Command line options
-
-_Black_ doesn't provide many options. You can list them by running `black --help`:
-
-```text
-Usage: black [OPTIONS] [SRC]...
-
- The uncompromising code formatter.
-
-Options:
- -c, --code TEXT Format the code passed in as a string.
- -l, --line-length INTEGER How many characters per line to allow.
- [default: 88]
-
- -t, --target-version [py27|py33|py34|py35|py36|py37|py38|py39]
- Python versions that should be supported by
- Black's output. [default: per-file auto-
- detection]
-
- --pyi Format all input files like typing stubs
- regardless of file extension (useful when
- piping source on standard input).
-
- -S, --skip-string-normalization
- Don't normalize string quotes or prefixes.
- -C, --skip-magic-trailing-comma
- Don't use trailing commas as a reason to
- split lines.
-
- --check Don't write the files back, just return the
- status. Return code 0 means nothing would
- change. Return code 1 means some files
- would be reformatted. Return code 123 means
- there was an internal error.
-
- --diff Don't write the files back, just output a
- diff for each file on stdout.
-
- --color / --no-color Show colored diff. Only applies when
- `--diff` is given.
-
- --fast / --safe If --fast given, skip temporary sanity
- checks. [default: --safe]
-
- --include TEXT A regular expression that matches files and
- directories that should be included on
- recursive searches. An empty value means
- all files are included regardless of the
- name. Use forward slashes for directories
- on all platforms (Windows, too). Exclusions
- are calculated first, inclusions later.
- [default: \.pyi?$]
-
- --exclude TEXT A regular expression that matches files and
- directories that should be excluded on
- recursive searches. An empty value means no
- paths are excluded. Use forward slashes for
- directories on all platforms (Windows, too).
- Exclusions are calculated first, inclusions
- later. [default: /(\.direnv|\.eggs|\.git|\.
- hg|\.mypy_cache|\.nox|\.tox|\.venv|venv|\.sv
- n|_build|buck-out|build|dist)/]
-
- --extend-exclude TEXT Like --exclude, but adds additional files
- and directories on top of the excluded
- ones (useful if you simply want to add to
- the default).
-
- --force-exclude TEXT Like --exclude, but files and directories
- matching this regex will be excluded even
- when they are passed explicitly as
- arguments.
-
-
- --stdin-filename TEXT The name of the file when passing it through
- stdin. Useful to make sure Black will
- respect --force-exclude option on some
- editors that rely on using stdin.
-
- -q, --quiet Don't emit non-error messages to stderr.
- Errors are still emitted; silence those with
- 2>/dev/null.
-
- -v, --verbose Also emit messages to stderr about files
- that were not changed or were ignored due to
- exclusion patterns.
-
- --version Show the version and exit.
- --config FILE Read configuration from FILE path.
- -h, --help Show this message and exit.
-```
-
-_Black_ is a well-behaved Unix-style command-line tool:
-
-- it does nothing if no sources are passed to it;
-- it will read from standard input and write to standard output if `-` is used as the
- filename;
-- it only outputs messages to users on standard error;
-- exits with code 0 unless an internal error occurred (or `--check` was used).
-
-### Using _Black_ with other tools
-
-While _Black_ enforces formatting that conforms to PEP 8, other tools may raise warnings
-about _Black_'s changes or will overwrite _Black_'s changes. A good example of this is
-[isort](https://pypi.org/p/isort). Since _Black_ is barely configurable, these tools
-should be configured to neither warn about nor overwrite _Black_'s changes.
-
-Actual details on _Black_ compatible configurations for various tools can be found in
-[compatible_configs](https://github.com/psf/black/blob/master/docs/compatible_configs.md#black-compatible-configurations).
-
-### Migrating your code style without ruining git blame
-
-A long-standing argument against moving to automated code formatters like _Black_ is
-that the migration will clutter up the output of `git blame`. This was a valid argument,
-but since Git version 2.23, Git natively supports
-[ignoring revisions in blame](https://git-scm.com/docs/git-blame#Documentation/git-blame.txt---ignore-revltrevgt)
-with the `--ignore-rev` option. You can also pass a file listing the revisions to ignore
-using the `--ignore-revs-file` option. The changes made by the revision will be ignored
-when assigning blame. Lines modified by an ignored revision will be blamed on the
-previous revision that modified those lines.
-
-So when migrating your project's code style to _Black_, reformat everything and commit
-the changes (preferably in one massive commit). Then put the full 40 characters commit
-identifier(s) into a file.
-
-```
-# Migrate code style to Black
-5b4ab991dede475d393e9d69ec388fd6bd949699
-```
-
-Afterwards, you can pass that file to `git blame` and see clean and meaningful blame
-information.
-
-```console
-$ git blame important.py --ignore-revs-file .git-blame-ignore-revs
-7a1ae265 (John Smith 2019-04-15 15:55:13 -0400 1) def very_important_function(text, file):
-abdfd8b0 (Alice Doe 2019-09-23 11:39:32 -0400 2) text = text.lstrip()
-7a1ae265 (John Smith 2019-04-15 15:55:13 -0400 3) with open(file, "r+") as f:
-7a1ae265 (John Smith 2019-04-15 15:55:13 -0400 4) f.write(formatted)
-```
+Further information can be found in our docs:
-You can even configure `git` to automatically ignore revisions listed in a file on every
-call to `git blame`.
+- [Usage and Configuration](https://black.readthedocs.io/en/stable/usage_and_configuration/index.html)
-```console
-$ git config blame.ignoreRevsFile .git-blame-ignore-revs
-```
+_Black_ is already [successfully used](https://github.com/psf/black#used-by) by many
+projects, small and big. _Black_ has a comprehensive test suite, with efficient parallel
+tests, and our own auto formatting and parallel Continuous Integration runner. Now that
+we have become stable, you should not expect large formatting changes in the future.
+Stylistic changes will mostly be responses to bug reports and support for new Python
+syntax. For more information please refer to the
+[The Black Code Style](https://black.readthedocs.io/en/stable/the_black_code_style/index.html).
+
+Also, as a safety measure which slows down processing, _Black_ will check that the
+reformatted code still produces a valid AST that is effectively equivalent to the
+original (see the
+[Pragmatism](https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#ast-before-and-after-formatting)
+section for details). If you're feeling confident, use `--fast`.
-**The one caveat is that GitHub and GitLab do not yet support ignoring revisions using
-their native UI of blame.** So blame information will be cluttered with a reformatting
-commit on those platforms. (If you'd like this feature, there's an open issue for
-[GitLab](https://gitlab.com/gitlab-org/gitlab/-/issues/31423) and please let GitHub
-know!)
+## The _Black_ code style
-### NOTE: This is a beta product
+_Black_ is a PEP 8 compliant opinionated formatter. _Black_ reformats entire files in
+place. Style configuration options are deliberately limited and rarely added. It doesn't
+take previous formatting into account (see
+[Pragmatism](https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#pragmatism)
+for exceptions).
-_Black_ is already [successfully used](https://github.com/psf/black#used-by) by many
-projects, small and big. It also sports a decent test suite. However, it is still very
-new. Things will probably be wonky for a while. This is made explicit by the "Beta"
-trove classifier, as well as by the "b" in the version number. What this means for you
-is that **until the formatter becomes stable, you should expect some formatting to
-change in the future**. That being said, no drastic stylistic changes are planned,
-mostly responses to bug reports.
+Our documentation covers the current _Black_ code style, but planned changes to it are
+also documented. They're both worth taking a look:
-Also, as a temporary safety measure, _Black_ will check that the reformatted code still
-produces a valid AST that is equivalent to the original. This slows it down. If you're
-feeling confident, use `--fast`.
+- [The _Black_ Code Style: Current style](https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html)
+- [The _Black_ Code Style: Future style](https://black.readthedocs.io/en/stable/the_black_code_style/future_style.html)
-## The _Black_ code style
+Changes to the _Black_ code style are bound by the Stability Policy:
-_Black_ is a PEP 8 compliant opinionated formatter. _Black_ reformats entire files in
-place. It is not configurable. It doesn't take previous formatting into account. Your
-main option of configuring _Black_ is that it doesn't reformat blocks that start with
-`# fmt: off` and end with `# fmt: on`, or lines that ends with `# fmt: skip`. Pay
-attention that `# fmt: on/off` have to be on the same level of indentation. To learn
-more about _Black_'s opinions, to go
-[the_black_code_style](https://github.com/psf/black/blob/master/docs/the_black_code_style.md).
+- [The _Black_ Code Style: Stability Policy](https://black.readthedocs.io/en/stable/the_black_code_style/index.html#stability-policy)
Please refer to this document before submitting an issue. What seems like a bug might be
intended behaviour.
-## Pragmatism
+### Pragmatism
Early versions of _Black_ used to be absolutist in some respects. They took after its
initial author. This was fine at the time as it made the implementation simpler and
there were not many users anyway. Not many edge cases were reported. As a mature tool,
-_Black_ does make some exceptions to rules it otherwise holds. This
-[section](https://github.com/psf/black/blob/master/docs/the_black_code_style.md#pragmatism)
-of `the_black_code_style` describes what those exceptions are and why this is the case.
+_Black_ does make some exceptions to rules it otherwise holds.
+
+- [The _Black_ code style: Pragmatism](https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#pragmatism)
Please refer to this document before submitting an issue just like with the document
above. What seems like a bug might be intended behaviour.
-## pyproject.toml
+## Configuration
_Black_ is able to read project-specific default values for its command line options
from a `pyproject.toml` file. This is especially useful for specifying custom
-`--include` and `--exclude`/`--extend-exclude` patterns for your project.
-
-**Pro-tip**: If you're asking yourself "Do I need to configure anything?" the answer is
-"No". _Black_ is all about sensible defaults.
-
-### What on Earth is a `pyproject.toml` file?
-
-[PEP 518](https://www.python.org/dev/peps/pep-0518/) defines `pyproject.toml` as a
-configuration file to store build system requirements for Python projects. With the help
-of tools like [Poetry](https://python-poetry.org/) or
-[Flit](https://flit.readthedocs.io/en/latest/) it can fully replace the need for
-`setup.py` and `setup.cfg` files.
-
-### Where _Black_ looks for the file
-
-By default _Black_ looks for `pyproject.toml` starting from the common base directory of
-all files and directories passed on the command line. If it's not there, it looks in
-parent directories. It stops looking when it finds the file, or a `.git` directory, or a
-`.hg` directory, or the root of the file system, whichever comes first.
-
-If you're formatting standard input, _Black_ will look for configuration starting from
-the current working directory.
-
-You can use a "global" configuration, stored in a specific location in your home
-directory. This will be used as a fallback configuration, that is, it will be used if
-and only if _Black_ doesn't find any configuration as mentioned above. Depending on your
-operating system, this configuration file should be stored as:
-
-- Windows: `~\.black`
-- Unix-like (Linux, MacOS, etc.): `$XDG_CONFIG_HOME/black` (`~/.config/black` if the
- `XDG_CONFIG_HOME` environment variable is not set)
-
-Note that these are paths to the TOML file itself (meaning that they shouldn't be named
-as `pyproject.toml`), not directories where you store the configuration. Here, `~`
-refers to the path to your home directory. On Windows, this will be something like
-`C:\\Users\UserName`.
-
-You can also explicitly specify the path to a particular file that you want with
-`--config`. In this situation _Black_ will not look for any other file.
-
-If you're running with `--verbose`, you will see a blue message if a file was found and
-used.
-
-Please note `blackd` will not use `pyproject.toml` configuration.
-
-### Configuration format
-
-As the file extension suggests, `pyproject.toml` is a
-[TOML](https://github.com/toml-lang/toml) file. It contains separate sections for
-different tools. _Black_ is using the `[tool.black]` section. The option keys are the
-same as long names of options on the command line.
-
-Note that you have to use single-quoted strings in TOML for regular expressions. It's
-the equivalent of r-strings in Python. Multiline strings are treated as verbose regular
-expressions by Black. Use `[ ]` to denote a significant space character.
+`--include` and `--exclude`/`--force-exclude`/`--extend-exclude` patterns for your
+project.
-
-Example
+You can find more details in our documentation:
-```toml
-[tool.black]
-line-length = 88
-target-version = ['py37']
-include = '\.pyi?$'
-extend-exclude = '''
-# A regex preceded with ^/ will apply only to files and directories
-# in the root of the project.
-^/foo.py # exclude a file named foo.py in the root of the project (in addition to the defaults)
-'''
-```
-
-
-
-### Lookup hierarchy
-
-Command-line options have defaults that you can see in `--help`. A `pyproject.toml` can
-override those defaults. Finally, options provided by the user on the command line
-override both.
-
-_Black_ will only ever use one `pyproject.toml` file during an entire run. It doesn't
-look for multiple files, and doesn't compose configuration from different levels of the
-file hierarchy.
-
-## Editor integration
-
-_Black_ can be integrated into many editors with plugins. They let you run _Black_ on
-your code with the ease of doing it in your editor. To get started using _Black_ in your
-editor of choice, please see
-[editor_integration](https://github.com/psf/black/blob/master/docs/editor_integration.md).
-
-Patches are welcome for editors without an editor integration or plugin! More
-information can be found in
-[editor_integration](https://github.com/psf/black/blob/master/docs/editor_integration.md#other-editors).
-
-## blackd
-
-`blackd` is a small HTTP server that exposes Black's functionality over a simple
-protocol. The main benefit of using it is to avoid paying the cost of starting up a new
-Black process every time you want to blacken a file. Please refer to
-[blackd](https://github.com/psf/black/blob/master/docs/blackd.md) to get the ball
-rolling.
-
-## black-primer
-
-`black-primer` is a tool built for CI (and humans) to have _Black_ `--check` a number of
-(configured in `primer.json`) Git accessible projects in parallel.
-[black_primer](https://github.com/psf/black/blob/master/docs/black_primer.md) has more
-information regarding its usage and configuration.
-
-(A PR adding Mercurial support will be accepted.)
-
-## Version control integration
-
-Use [pre-commit](https://pre-commit.com/). Once you
-[have it installed](https://pre-commit.com/#install), add this to the
-`.pre-commit-config.yaml` in your repository:
-
-```yaml
-repos:
- - repo: https://github.com/psf/black
- rev: 20.8b1 # Replace by any tag/version: https://github.com/psf/black/tags
- hooks:
- - id: black
- language_version: python3 # Should be a command that runs python3.6+
-```
-
-Then run `pre-commit install` and you're ready to go.
-
-Avoid using `args` in the hook. Instead, store necessary configuration in
-`pyproject.toml` so that editors and command-line usage of Black all behave consistently
-for your project. See _Black_'s own
-[pyproject.toml](https://github.com/psf/black/blob/master/pyproject.toml) for an
-example.
-
-If you're already using Python 3.7, switch the `language_version` accordingly. Finally,
-`stable` is a branch that tracks the latest release on PyPI. If you'd rather run on
-master, this is also an option.
+- [The basics: Configuration via a file](https://black.readthedocs.io/en/stable/usage_and_configuration/the_basics.html#configuration-via-a-file)
-## GitHub Actions
+And if you're looking for more general configuration documentation:
-Create a file named `.github/workflows/black.yml` inside your repository with:
+- [Usage and Configuration](https://black.readthedocs.io/en/stable/usage_and_configuration/index.html)
-```yaml
-name: Lint
-
-on: [push, pull_request]
-
-jobs:
- lint:
- runs-on: ubuntu-latest
- steps:
- - uses: actions/checkout@v2
- - uses: actions/setup-python@v2
- - uses: psf/black@stable
- with:
- args: ". --check"
-```
-
-### Inputs
-
-#### `black_args`
-
-**optional**: Black input arguments. Defaults to `. --check --diff`.
-
-## Ignoring unmodified files
-
-_Black_ remembers files it has already formatted, unless the `--diff` flag is used or
-code is passed via standard input. This information is stored per-user. The exact
-location of the file depends on the _Black_ version and the system on which _Black_ is
-run. The file is non-portable. The standard location on common operating systems is:
-
-- Windows:
- `C:\\Users\