black [OPTIONS] [SRC]...
Options:
- -l, --line-length INTEGER Where to wrap around. [default: 88]
- --py36 Allow using Python 3.6-only syntax on all input
- files. This will put trailing commas in function
- signatures and calls also after *args and
- **kwargs. [default: per-file auto-detection]
- --pyi Format all input files like typing stubs
- regardless of file extension (useful when piping
- source on standard input).
+ -l, --line-length INTEGER How many characters per line to allow.
+ [default: 88]
+ -t, --target-version [py27|py33|py34|py35|py36|py37|py38]
+ Python versions that should be supported by
+ Black's output. [default: per-file auto-
+ detection]
+ --py36 Allow using Python 3.6-only syntax on all
+ input files. This will put trailing commas
+ in function signatures and calls also after
+ *args and **kwargs. Deprecated; use
+ --target-version instead. [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.
- --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.
- --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. On Windows, use forward
- slashes for directories. [default: \.pyi?$]
- --exclude TEXT A regular expression that matches files and
- directories that should be excluded on
- recursive searches. On Windows, use forward
- slashes for directories. [default:
- build/|buck-out/|dist/|_build/|\.git/|\.hg/|
- \.mypy_cache/|\.tox/|\.venv/]
- -q, --quiet Don't emit non-error messages to stderr. Errors
- are still emitted, silence those with
- 2>/dev/null.
- -v, --verbose Also emit messages to stderr about files
- that were not changed or were ignored due to
- --exclude=.
- --version Show the version and exit.
- --config PATH Read configuration from PATH.
- --help Show this message and exit.
+ Don't normalize string quotes or prefixes.
+ --check Don't write the files back, just return the
+ status. Return code 0 means nothing would
+ change. Return code 1 means some files
+ would be reformatted. Return code 123 means
+ there was an internal error.
+ --diff Don't write the files back, just output a
+ diff for each file on stdout.
+ --fast / --safe If --fast given, skip temporary sanity
+ checks. [default: --safe]
+ --include TEXT A regular expression that matches files and
+ directories that should be included on
+ recursive searches. An empty value means
+ all files are included regardless of the
+ name. Use forward slashes for directories
+ on all platforms (Windows, too). Exclusions
+ are calculated first, inclusions later.
+ [default: \.pyi?$]
+ --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: /(\.eggs|\.git|\.hg|\.mypy
+ _cache|\.nox|\.tox|\.venv|_build|buck-
+ out|build|dist)/]
+ -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
+ --exclude=.
+ --version Show the version and exit.
+ --config PATH Read configuration from PATH.
+ -h, --help Show this message and exit.
```
*Black* is a well-behaved Unix-style command-line tool:
*Black* reformats entire files in place. It is not configurable. It
doesn't take previous formatting into account. It doesn't reformat
-blocks that start with `# fmt: off` and end with `# fmt: on`. It also
+blocks that start with `# fmt: off` and end with `# fmt: on`. `# fmt: on/off`
+have to be on the same level of indentation. It also
recognizes [YAPF](https://github.com/google/yapf)'s block comments to
the same effect, as a courtesy for straddling code.
```py3
# in:
-TracebackException.from_exception(exc, limit, lookup_lines, capture_locals)
+ImportantClass.important_method(exc, limit, lookup_lines, capture_locals, extra_argument)
# out:
-TracebackException.from_exception(
- exc, limit, lookup_lines, capture_locals
+ImportantClass.important_method(
+ exc, limit, lookup_lines, capture_locals, extra_argument
)
```
```py3
# in:
-def very_important_function(template: str, *variables, file: os.PathLike, debug: bool = False):
+def very_important_function(template: str, *variables, file: os.PathLike, engine: str, header: bool = True, debug: bool = False):
"""Applies `variables` to the `template` and writes to `file`."""
with open(file, 'w') as f:
...
template: str,
*variables,
file: os.PathLike,
+ engine: str,
+ header: bool = True,
debug: bool = False,
):
"""Applies `variables` to the `template` and writes to `file`."""
multi_line_output=3
include_trailing_comma=True
force_grid_wrap=0
-combine_as_imports=True
+use_parentheses=True
line_length=88
```
The equivalent command line is:
```
-$ isort --multi-line=3 --trailing-comma --force-grid-wrap=0 --combine-as --line-width=88 [ file.py ]
+$ isort --multi-line=3 --trailing-comma --force-grid-wrap=0 --use-parentheses --line-width=88 [ file.py ]
```
</details>
```
You'll find *Black*'s own .flake8 config file is configured like this.
-If you're curious about the reasoning behind B950, Bugbear's documentation
+If you're curious about the reasoning behind B950,
+[Bugbear's documentation](https://github.com/PyCQA/flake8-bugbear#opinionated-warnings)
explains it. The tl;dr is "it's like highway speed limits, we won't
bother you if you overdo it by a few km/h".
[#26](https://github.com/ambv/black/issues/26) for details).
Why settle on double quotes? They anticipate apostrophes in English
-text. They match the docstring standard described in PEP 257. An
-empty string in double quotes (`""`) is impossible to confuse with
+text. They match the docstring standard described in [PEP 257](https://www.python.org/dev/peps/pep-0257/#what-is-a-docstring).
+An empty string in double quotes (`""`) is impossible to confuse with
a one double-quote regardless of fonts and syntax highlighting used.
On top of this, double quotes for strings are consistent with C which
Python interacts a lot with.
*Black* standardizes most numeric literals to use lowercase letters for the
syntactic parts and uppercase letters for the digits themselves: `0xAB`
instead of `0XAB` and `1e10` instead of `1E10`. Python 2 long literals are
-styled as `2L` instead of `2l` to avoid confusion between `l` and `1`. In
-Python 3.6+, *Black* adds underscores to long numeric literals to aid
-readability: `100000000` becomes `100_000_000`.
+styled as `2L` instead of `2l` to avoid confusion between `l` and `1`.
+
### Line breaks & binary operators
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
```toml
[tool.black]
line-length = 88
-py36 = true
+target-version = ['py37']
include = '\.pyi?$'
exclude = '''
-/(
- \.git
- | \.hg
- | \.mypy_cache
- | \.tox
- | \.venv
- | _build
- | buck-out
- | build
- | dist
-
- # The following are specific to Black, you probably don't want those.
- | blib2to3
- | tests/data
-)/
+
+(
+ /(
+ \.eggs # exclude a few common directories in the
+ | \.git # root of the project
+ | \.hg
+ | \.mypy_cache
+ | \.tox
+ | \.venv
+ | _build
+ | buck-out
+ | build
+ | dist
+ )/
+ | foo.py # also separately exclude a file named foo.py in
+ # the root of the project
+)
'''
```
Use [proofit404/blacken](https://github.com/proofit404/blacken).
-### PyCharm
+### PyCharm/IntelliJ IDEA
1. Install `black`.
%LocalAppData%\Programs\Python\Python36-32\Scripts\black.exe # possible location
```
-3. Open External tools in PyCharm with `File -> Settings -> Tools -> External Tools`.
+3. Open External tools in PyCharm/IntelliJ IDEA
+
+ On macOS:
+
+```PyCharm -> Preferences -> Tools -> External Tools```
+
+ On Windows / Linux / BSD:
+
+```File -> Settings -> Tools -> External Tools```
4. Click the + icon to add a new external tool with the following values:
- Name: Black
- Description: Black is the uncompromising Python code formatter.
- Program: <install_location_from_step_2>
- - Arguments: `$FilePath$`
+ - Arguments: `"$FilePath$"`
5. Format the currently opened file by selecting `Tools -> External Tools -> black`.
- - Alternatively, you can set a keyboard shortcut by navigating to `Preferences -> Keymap -> External Tools -> External Tools - Black`.
+ - Alternatively, you can set a keyboard shortcut by navigating to `Preferences or Settings -> Keymap -> External Tools -> External Tools - Black`.
6. Optionally, run Black on every file save:
1. Make sure you have the [File Watcher](https://plugins.jetbrains.com/plugin/7177-file-watchers) plugin installed.
- 2. Go to `Preferences -> Tools -> File Watchers` and click `+` to add a new watcher:
+ 2. Go to `Preferences or Settings -> Tools -> File Watchers` and click `+` to add a new watcher:
- Name: Black
- File type: Python
- Scope: Project Files
- Program: <install_location_from_step_2>
- Arguments: `$FilePath$`
- - Output paths to refresh: `$FilePathRelativeToProjectRoot$`
+ - Output paths to refresh: `$FilePath$`
- Working directory: `$ProjectFileDir$`
+ - Uncheck "Auto-save edited files to trigger the watcher"
### Vim
To install with [vim-plug](https://github.com/junegunn/vim-plug):
```
-Plug 'ambv/black',
+Plug 'ambv/black'
```
or with [Vundle](https://github.com/VundleVim/Vundle.vim):
Use [sublack plugin](https://github.com/jgirardet/sublack).
-### IPython Notebook Magic
+### Jupyter Notebook Magic
Use [blackcellmagic](https://github.com/csurfer/blackcellmagic).
passed). *Black* will still emit messages on stderr but that shouldn't
affect your use case.
-This can be used for example with PyCharm's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html).
+This can be used for example with PyCharm's or IntelliJ's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html).
## blackd
### Protocol
`blackd` only accepts `POST` requests at the `/` path. The body of the request
-should contain the python source code to be formatted, encoded
+should contain the python source code to be formatted, encoded
according to the `charset` field in the `Content-Type` request header. If no
`charset` is specified, `blackd` assumes `UTF-8`.
There are a few HTTP headers that control how the source is formatted. These
correspond to command line flags for *Black*. There is one exception to this:
`X-Protocol-Version` which if present, should have the value `1`, otherwise the
-request is rejected with `HTTP 501` (Not Implemented).
+request is rejected with `HTTP 501` (Not Implemented).
The headers controlling how code is formatted are:
passed the `--fast` command line flag.
- `X-Python-Variant`: if set to `pyi`, `blackd` will act as *Black* does when
passed the `--pyi` command line flag. Otherwise, its value must correspond to
- a Python version. If this value represents at least Python 3.6, `blackd` will
- act as *Black* does when passed the `--py36` command line flag.
+ a Python version or a set of comma-separated Python versions, optionally
+ prefixed with `py`. For example, to request code that is compatible
+ with Python 3.5 and 3.6, set the header to `py3.5,py3.6`.
If any of these headers are set to invalid values, `blackd` returns a `HTTP 400`
error response, mentioning the name of the problematic header in the message body.
## Change Log
+### 19.3b1
+
+* fix bug that led *Black* format some code with a line length target of 1
+ (#762)
+
+### 19.3b0
+
+* new option `--target-version` to control which Python versions
+ *Black*-formatted code should target (#618)
+
+* deprecated `--py36` (use `--target-version=py36` instead) (#724)
+
+* *Black* no longer normalizes numeric literals to include `_` separators (#696)
+
+* long `del` statements are now split into multiple lines (#698)
+
+* type comments are no longer mangled in function signatures
+
+* improved performance of formatting deeply nested data structures (#509)
+
+* *Black* now properly formats multiple files in parallel on
+ Windows (#632)
+
+* *Black* now creates cache files atomically which allows it to be used
+ in parallel pipelines (like `xargs -P8`) (#673)
+
+* *Black* now correctly indents comments in files that were previously
+ formatted with tabs (#262)
+
+* `blackd` now supports CORS (#622)
+
### 18.9b0
* numeric literals are now formatted by *Black* (#452, #461, #464, #469):
* numeric literals are normalized to include `_` separators on Python 3.6+ code
+ * added `--skip-numeric-underscore-normalization` to disable the above behavior and
+ leave numeric underscores as they were in the input
+
* code with `_` in numeric literals is recognized as Python 3.6+
- * most letters in numeric literals are lowercased (e.g., in `1e10` or `0xab`)
+ * most letters in numeric literals are lowercased (e.g., in `1e10`, `0x01`)
+
+ * hexadecimal digits are always uppercased (e.g. `0xBADC0DE`)
* added `blackd`, see [its documentation](#blackd) for more info (#349)
* adjacent string literals are now correctly split into multiple lines (#463)
+* trailing comma is now added to single imports that don't fit on a line (#250)
+
* cache is now populated when `--check` is successful for a file which speeds up
consecutive checks of properly formatted unmodified files (#448)
-* code with `_` in numeric literals is recognized as Python 3.6+ (#461)
+* whitespace at the beginning of the file is now removed (#399)
+
+* fixed mangling [pweave](http://mpastell.com/pweave/) and
+ [Spyder IDE](https://pythonhosted.org/spyder/) special comments (#532)
* fixed unstable formatting when unpacking big tuples (#267)
to be a bad idea (#415)
-
### 18.6b4
* hotfix: don't freeze when multiple comments directly precede `# fmt: off` (#371)
* [Christian Heimes](mailto:christian@python.org)
* [Daniel M. Capella](mailto:polycitizen@gmail.com)
* [Eli Treuherz](mailto:eli@treuherz.com)
+* hauntsaninja
* Hugo van Kemenade
* [Ivan Katanić](mailto:ivan.katanic@gmail.com)
* [Jonas Obrist](mailto:ojiidotch@gmail.com)
* [Luka Sterbic](mailto:luka.sterbic@gmail.com)
* [Miguel Gaiowski](mailto:miggaiowski@gmail.com)
* [Miroslav Shubernetskiy](mailto:miroslav@miki725.com)
-* [Neraste](neraste.herr10@gmail.com)
+* [Neraste](mailto:neraste.herr10@gmail.com)
* [Osaetin Daniel](mailto:osaetindaniel@gmail.com)
* [Peter Bengtsson](mailto:mail@peterbe.com)
* [Stavros Korokithakis](mailto:hi@stavros.io)
* [Sunil Kapil](mailto:snlkapil@gmail.com)
+* [Utsav Shah](mailto:ukshah2@illinois.edu)
* [Vishwas B Sharma](mailto:sharma.vishwas88@gmail.com)
+* [Chuck Wooters](mailto:chuck.wooters@microsoft.com)