-# black
+
+<h2 align="center">The Uncompromising Code Formatter</h2>
-[](https://travis-ci.org/ambv/black)
+<p align="center">
+<a href="https://travis-ci.org/ambv/black"><img alt="Build Status" src="https://travis-ci.org/ambv/black.svg?branch=master"></a>
+<a href="http://black.readthedocs.io/en/latest/?badge=latest"><img alt="Documentation Status" src="http://readthedocs.org/projects/black/badge/?version=latest"></a>
+<a href="https://coveralls.io/github/ambv/black?branch=master"><img alt="Coverage Status" src="https://coveralls.io/repos/github/ambv/black/badge.svg?branch=master"></a>
+<a href="https://github.com/ambv/black/blob/master/LICENSE"><img alt="License: MIT" src="http://black.readthedocs.io/en/latest/_static/license.svg"></a>
+<a href="https://pypi.python.org/pypi/black"><img alt="PyPI" src="http://black.readthedocs.io/en/latest/_static/pypi.svg"></a>
+<a href="https://github.com/ambv/black"><img alt="Code style: black" src="https://img.shields.io/badge/code%20style-black-000000.svg"></a>
+</p>
-> Any color you like.
+> “Any color you like.”
*Black* is the uncompromising Python code formatter. By using it, you
possible.
-## NOTE: This is an early pre-release
+## Installation and Usage
-*Black* can already successfully format itself and the standard library.
-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
-"Alpha" trove classifier, as well as by the "a" 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**.
+### Installation
-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``.
+*Black* can be installed by running `pip install black`. It requires
+Python 3.6.0+ to run but you can reformat Python 2 code with it, too.
-## Usage
+### Usage
-*Black* can be installed by running `pip install black`.
+To get started right away with sensible defaults:
```
+black {source_file_or_directory}
+```
+
+### Command line options
+
+Black doesn't provide many options. You can list them by running
+`black --help`:
+
+```text
black [OPTIONS] [SRC]...
Options:
-l, --line-length INTEGER Where to wrap around. [default: 88]
+ --check Don't write back the files, 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.
--fast / --safe If --fast given, skip temporary sanity checks.
[default: --safe]
--version Show the version and exit.
--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 occured (or `--check` was
+ used).
+
+
+### NOTE: This is an early pre-release
+
+*Black* can already successfully format itself and the standard library.
+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
+"Alpha" trove classifier, as well as by the "a" 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**.
+
+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 philosophy behind *Black*
+
+## The *Black* code style
*Black* reformats entire files in place. It is not configurable. It
doesn't take previous formatting into account. It doesn't reformat
the same effect, as a courtesy for straddling code.
-### How *Black* formats files
+### How *Black* wraps lines
*Black* ignores previous formatting and applies uniform horizontal
and vertical whitespace to your code. The rules for horizontal
whitespace are pretty obvious and can be summarized as: do whatever
-makes `pycodestyle` happy.
+makes `pycodestyle` happy. The coding style used by *Black* can be
+viewed as a strict subset of PEP 8.
As for vertical whitespace, *Black* tries to render one full expression
or simple statement per line. If this fits the allotted line length,
great.
```py3
# in:
+
l = [1,
2,
3,
]
# out:
+
l = [1, 2, 3]
```
brackets and put that in a separate indented line.
```py3
# in:
+
l = [[n for n in list_bosses()], [n for n in list_employees()]]
# out:
+
l = [
[n for n in list_bosses()], [n for n in list_employees()]
]
separate lines.
```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, debug: bool = False):
"""Applies `variables` to the `template` and writes to `file`."""
with open(file, 'w') as f:
...
# out:
+
def very_important_function(
template: str,
*variables,
- *,
file: os.PathLike,
debug: bool = False,
):
indentation level (like the arguments list and the docstring in the
example above).
-Unnecessary trailing commas are removed if an expression fits in one
-line. This makes it 1% more likely that your line won't exceed the
-allotted line length limit.
-
-*Black* avoids spurious vertical whitespace. This is in the spirit of
-PEP 8 which says that in-function vertical whitespace should only be
-used sparingly. One exception is control flow statements: *Black* will
-always emit an extra empty line after ``return``, ``raise``, ``break``,
-``continue``, and ``yield``. This is to make changes in control flow
-more prominent to readers of your code.
-
-That's it. The rest of the whitespace formatting rules follow PEP 8 and
-are designed to keep `pycodestyle` quiet.
-
### Line length
bother you if you overdo it by a few km/h".
-### Editor integration
+### Empty lines
+
+*Black* avoids spurious vertical whitespace. This is in the spirit of
+PEP 8 which says that in-function vertical whitespace should only be
+used sparingly. One exception is control flow statements: *Black* will
+always emit an extra empty line after ``return``, ``raise``, ``break``,
+``continue``, and ``yield``. This is to make changes in control flow
+more prominent to readers of your code.
+
+*Black* will allow single empty lines inside functions, and single and
+double empty lines on module level left by the original editors, except
+when they're within parenthesized expressions. Since such expressions
+are always reformatted to fit minimal space, this whitespace is lost.
+
+It will also insert proper spacing before and after function definitions.
+It's one line before and after inner functions and two lines before and
+after module-level functions. *Black* will put those empty lines also
+between the function definition and any standalone comments that
+immediately precede the given function. If you want to comment on the
+entire function, use a docstring or put a leading comment in the function
+body.
+
+
+### Trailing commas
+
+*Black* will add trailing commas to expressions that are split
+by comma where each element is on its own line. This includes function
+signatures.
+
+Unnecessary trailing commas are removed if an expression fits in one
+line. This makes it 1% more likely that your line won't exceed the
+allotted line length limit. Moreover, in this scenario, if you added
+another argument to your call, you'd probably fit it in the same line
+anyway. That doesn't make diffs any larger.
+
+One exception to removing trailing commas is tuple expressions with
+just one element. In this case *Black* won't touch the single trailing
+comma as this would unexpectedly change the underlying data type. Note
+that this is also the case when commas are used while indexing. This is
+a tuple in disguise: ```numpy_array[3, ]```.
+
+One exception to adding trailing commas is function signatures
+containing `*`, `*args`, or `**kwargs`. In this case a trailing comma
+is only safe to use on Python 3.6. *Black* will detect if your file is
+already 3.6+ only and use trailing commas in this situation. If you
+wonder how it knows, it looks for f-strings and existing use of trailing
+commas in function signatures that have stars in them. In other words,
+if you'd like a trailing comma in this situation and *Black* didn't
+recognize it was safe to do so, put it there manually and *Black* will
+keep it.
-There is currently no integration with any text editors. Vim and
-Atom/Nuclide integration is planned by the author, others will require
-external contributions.
+
+## Editor integration
+
+### Emacs
+
+Use [proofit404/blacken](https://github.com/proofit404/blacken).
+
+
+### Vim
+
+Commands and shortcuts:
+
+* `,=` or `:Black` to format the entire file (ranges not supported);
+* `:BlackUpgrade` to upgrade *Black* inside the virtualenv;
+* `:BlackVersion` to get the current version of *Black* inside the
+ virtualenv.
+
+Configuration:
+* `g:black_fast` (defaults to `0`)
+* `g:black_linelength` (defaults to `88`)
+* `g:black_virtualenv` (defaults to `~/.vim/black`)
+
+To install, copy the plugin from [vim/plugin/black.vim](https://github.com/ambv/black/tree/master/vim/plugin/black.vim).
+Let me know if this requires any changes to work with Vim 8's builtin
+`packadd`, or Pathogen, or Vundle, and so on.
+
+This plugin **requires Vim 7.0+ built with Python 3.6+ support**. It
+needs Python 3.6 to be able to run *Black* inside the Vim process which
+is much faster than calling an external command.
+
+On first run, the plugin creates its own virtualenv using the right
+Python version and automatically installs *Black*. You can upgrade it later
+by calling `:BlackUpgrade` and restarting Vim.
+
+If you need to do anything special to make your virtualenv work and
+install *Black* (for example you want to run a version from master), just
+create a virtualenv manually and point `g:black_virtualenv` to it.
+The plugin will use it.
+
+**How to get Vim with Python 3.6?**
+On Ubuntu 17.10 Vim comes with Python 3.6 by default.
+On macOS with HomeBrew run: `brew install vim --with-python3`.
+When building Vim from source, use:
+`./configure --enable-python3interp=yes`. There's many guides online how
+to do this.
+
+
+### Visual Studio Code
+
+Use [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode).
+
+
+### Other editors
+
+Atom/Nuclide integration is planned by the author, others will
+require external contributions.
Patches welcome! ✨ 🍰 ✨
+Any tool that can pipe code through *Black* using its stdio mode (just
+[use `-` as the file name](http://www.tldp.org/LDP/abs/html/special-chars.html#DASHREF2)).
+The formatted code will be returned on stdout (unless `--check` was
+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).
+
## Testimonials
> This vastly improves the formatting of our code. Thanks a ton!
-## Tests
+## Show your style
-Just run:
+Use the badge in your project's README.md:
+```markdown
+[](https://github.com/ambv/black)
```
-python setup.py test
-```
-
-## This tool requires Python 3.6.0+ to run
-
-But you can reformat Python 2 code with it, too. *Black* is able to parse
-all of the new syntax supported on Python 3.6 but also *effectively all*
-the Python 2 syntax at the same time, as long as you're not using print
-statements.
-By making the code exclusively Python 3.6+, I'm able to focus on the
-quality of the formatting and re-use all the nice features of the new
-releases (check out [pathlib](docs.python.org/3/library/pathlib.html) or
-f-strings) instead of wasting cycles on Unicode compatibility, and so on.
+Looks like this: [](https://github.com/ambv/black)
## License
MIT
-## Contributing
+## Contributing to Black
In terms of inspiration, *Black* is about as configurable as *gofmt* and
*rustfmt* are. This is deliberate.
ready to embrace *Black* yet. Such changes are unlikely to get accepted.
You can still try but prepare to be disappointed.
+More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
+
## Change Log
+### 18.3a5 (unreleased)
+
+* fixed 18.3a4 regression: don't crash and burn on empty lines with
+ trailing whitespace (#80)
+
+* only allow up to two empty lines on module level and only single empty
+ lines within functions (#74)
+
+
+### 18.3a4
+
+* `# fmt: off` and `# fmt: on` are implemented (#5)
+
+* automatic detection of deprecated Python 2 forms of print statements
+ and exec statements in the formatted file (#49)
+
+* use proper spaces for complex expressions in default values of typed
+ function arguments (#60)
+
+* only return exit code 1 when --check is used (#50)
+
+* don't remove single trailing commas from square bracket indexing
+ (#59)
+
+* don't omit whitespace if the previous factor leaf wasn't a math
+ operator (#55)
+
+* omit extra space in kwarg unpacking if it's the first argument (#46)
+
+* omit extra space in [Sphinx auto-attribute comments](http://www.sphinx-doc.org/en/stable/ext/autodoc.html#directive-autoattribute)
+ (#68)
+
+
+### 18.3a3
+
+* don't remove single empty lines outside of bracketed expressions
+ (#19)
+
+* added ability to pipe formatting from stdin to stdin (#25)
+
+* restored ability to format code with legacy usage of `async` as
+ a name (#20, #42)
+
+* even better handling of numpy-style array indexing (#33, again)
+
+
+### 18.3a2
+
+* changed positioning of binary operators to occur at beginning of lines
+ instead of at the end, following [a recent change to PEP8](https://github.com/python/peps/commit/c59c4376ad233a62ca4b3a6060c81368bd21e85b)
+ (#21)
+
+* ignore empty bracket pairs while splitting. This avoids very weirdly
+ looking formattings (#34, #35)
+
+* remove a trailing comma if there is a single argument to a call
+
+* if top level functions were separated by a comment, don't put four
+ empty lines after the upper function
+
+* fixed unstable formatting of newlines with imports
+
+* fixed unintentional folding of post scriptum standalone comments
+ into last statement if it was a simple statement (#18, #28)
+
+* fixed missing space in numpy-style array indexing (#33)
+
+* fixed spurious space after star-based unary expressions (#31)
+
+
### 18.3a1
+* added `--check`
+
+* only put trailing commas in function signatures and calls if it's
+ safe to do so. If the file is Python 3.6+ it's always safe, otherwise
+ only safe if there are no `*args` or `**kwargs` used in the signature
+ or call. (#8)
+
* fixed invalid spacing of dots in relative imports (#6, #13)
+* fixed invalid splitting after comma on unpacked variables in for-loops
+ (#23)
+
+* fixed spurious space in parenthesized set expressions (#7)
+
+* fixed spurious space after opening parentheses and in default
+ arguments (#14, #17)
+
+* fixed spurious space after unary operators when the operand was
+ a complex expression (#15)
+
### 18.3a0
## Authors
Glued together by [Łukasz Langa](mailto:lukasz@langa.pl).
+
+Maintained with [Carol Willing](mailto:carolcode@willingconsulting.com)
+and [Carl Meyer](mailto:carl@oddbird.net).
+
+Multiple contributions by:
+* [Artem Malyshev](mailto:proofit404@gmail.com)
+* [Daniel M. Capella](mailto:polycitizen@gmail.com)
+* [Eli Treuherz](mailto:eli.treuherz@cgi.com)
+* Hugo van Kemenade
+* [Mika⠙](mailto:mail@autophagy.io)
+* [Osaetin Daniel](mailto:osaetindaniel@gmail.com)
projects / etc / vim.git / blobdiff