Options:
-l, --line-length INTEGER Where to wrap around. [default: 88]
- --check Don't write back the files, just return the
+ --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]
+ -q, --quiet Don't emit non-error messages to stderr. Errors
+ are still emitted, silence those with
+ 2>/dev/null.
--version Show the version and exit.
--help Show this message and exit.
```
debug: bool = False,
):
"""Applies `variables` to the `template` and writes to `file`."""
- with open(file, 'w') as f:
+ with open(file, "w") as f:
...
```
recognize it was safe to do so, put it there manually and *Black* will
keep it.
+### Strings
+
+*Black* prefers double quotes (`"` and `"""`) over single quotes (`'`
+and `'''`). It will replace the latter with the former as long as it
+does not result in more backslash escapes than before.
+
+The main reason to standardize on a single form of quotes is aesthetics.
+Having one kind of quotes everywhere reduces reader distraction.
+It will also enable a future version of *Black* to merge consecutive
+string literals that ended up on the same line (see
+[#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
+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.
+
+On certain keyboard layouts like US English, typing single quotes is
+a bit easier than double quotes. The latter requires use of the Shift
+key. My recommendation here is to keep using whatever is faster to type
+and let *Black* handle the transformation.
+
+### Line Breaks & Binary Operators
+
+*Black* will break a line before a binary operator when splitting a block
+of code over multiple lines. This is so that *Black* is compliant with the
+recent changes in the [PEP 8](https://www.python.org/dev/peps/pep-0008/#should-a-line-break-before-or-after-a-binary-operator)
+style guide, which emphasizes that this approach improves readability.
+
+This behaviour may raise ``W503 line break before binary operator`` warnings in
+style guide enforcement tools like Flake8. Since ``W503`` is not PEP 8 compliant,
+you should tell Flake8 to ignore these warnings.
+
+### Parentheses
+
+Some parentheses are optional in the Python grammar. Any expression can
+be wrapped in a pair of parentheses to form an atom. There are a few
+interesting cases:
+
+- `if (...):`
+- `while (...):`
+- `for (...) in (...):`
+- `assert (...), (...)`
+- `from X import (...)`
+
+In those cases, parentheses are removed when the entire statement fits
+in one line, or if the inner expression doesn't have any delimiters to
+further split on. Otherwise, the parentheses are always added.
+
## Editor integration
-* Visual Studio Code: [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode)
-* Emacs: [proofit404/blacken](https://github.com/proofit404/blacken)
+### Emacs
+
+Use [proofit404/blacken](https://github.com/proofit404/blacken).
+
+
+### PyCharm
+
+1. Install `black`.
+
+ $ pip install black
+
+2. Locate your `black` installation folder.
+
+ On MacOS / Linux / BSD:
+
+ $ which black
+ /usr/local/bin/black # possible location
+
+ On Windows:
+
+ $ where black
+ %LocalAppData%\Programs\Python\Python36-32\Scripts\black.exe # possible location
+
+3. Open External tools in PyCharm with `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: $FilePath$
+
+5. Format the currently opened file by selecting `Tools -> External Tools -> black`.
+ - Alternatively, you can set a keyboard shortcut by navigating to `Preferences -> Keymap`.
+
+
+### 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).
+
+### SublimeText 3
+
+Use [sublack plugin](https://github.com/jgirardet/sublack).
+
+### 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)).
passed). *Black* will still emit messages on stderr but that shouldn't
affect your use case.
-Vim and Atom/Nuclide integration is planned by the author, others will
-require external contributions.
+This can be used for example with PyCharm's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html).
-Patches welcome! ✨ 🍰 ✨
+
+## 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/ambv/black
+ rev: stable
+ hooks:
+ - id: black
+ args: [--line-length=88, --safe]
+ python_version: python3.6
+```
+Then run `pre-commit install` and you're ready to go.
+
+`args` in the above config is optional but shows you how you can change
+the line length if you really need to. If you're already using Python
+3.7, switch the `python_version` accordingly. Finally, `stable` is a tag
+that is pinned to the latest release on PyPI. If you'd rather run on
+master, this is also an option.
+
+
+## Ignoring non-modified files
+
+*Black* remembers files it 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\<username>\AppData\Local\black\black\Cache\<version>\cache.pickle`
+* macOS: `/Users/<username>/Library/Caches/black/<version>/cache.pickle`
+* Linux: `/home/<username>/.cache/black/<version>/cache.pickle`
## Testimonials
## Change Log
-### 18.3a5 (unreleased)
+### 18.4a3 (unreleased)
+
+* added a "cache"; files already reformatted that haven't changed on disk
+ won't be reformatted again (#109)
+
+* generalized star expression handling, including double stars; this
+ fixes multiplication making expressions "unsafe" for trailing commas (#132)
+
+* fixed parsing of complex expressions after star and double stars in
+ function parameters (#2)
+
+* fixed invalid splitting on comma in lambda arguments (#133)
+
+### 18.4a2
+
+* fixed parsing of unaligned standalone comments (#99, #112)
+
+* fixed placement of dictionary unpacking inside dictionary literals (#111)
+
+* Vim plugin now works on Windows, too
+
+* fixed unstable formatting when encountering unnecessarily escaped quotes
+ in a string (#120)
+
+
+### 18.4a1
+
+* added `--quiet` (#78)
+
+* added automatic parentheses management (#4)
+
+* added [pre-commit](https://pre-commit.com) integration (#103, #104)
+
+* fixed reporting on `--check` with multiple files (#101, #102)
+
+* fixed removing backslash escapes from raw strings (#100, #105)
+
+
+### 18.4a0
+
+* added `--diff` (#87)
+
+* add line breaks before all delimiters, except in cases like commas, to
+ better comply with PEP 8 (#73)
+
+* standardize string literals to use double quotes (almost) everywhere
+ (#75)
+
+* fixed handling of standalone comments within nested bracketed
+ expressions; Black will no longer produce super long lines or put all
+ standalone comments at the end of the expression (#22)
* fixed 18.3a4 regression: don't crash and burn on empty lines with
trailing whitespace (#80)
+* fixed 18.3a4 regression: `# yapf: disable` usage as trailing comment
+ would cause Black to not emit the rest of the file (#95)
+
+* when CTRL+C is pressed while formatting many files, Black no longer
+ freaks out with a flurry of asyncio-related exceptions
+
* only allow up to two empty lines on module level and only single empty
lines within functions (#74)
Glued together by [Łukasz Langa](mailto:lukasz@langa.pl).
-Maintained with [Carol Willing](mailto:carolcode@willingconsulting.com)
-and [Carl Meyer](mailto:carl@oddbird.net).
+Maintained with [Carol Willing](mailto:carolcode@willingconsulting.com),
+[Carl Meyer](mailto:carl@oddbird.net),
+[Mika Naylor](mailto:mail@autophagy.io), and
+[Zsolt Dollenstein](mailto:zsol.zsol@gmail.com).
Multiple contributions by:
+* [Anthony Sottile](mailto:asottile@umich.edu)
* [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)
+* [Ivan Katanić](mailto:ivan.katanic@gmail.com)
+* [Jonas Obrist](mailto:ojiidotch@gmail.com)
* [Osaetin Daniel](mailto:osaetindaniel@gmail.com)