X-Git-Url: https://git.madduck.net/etc/vim.git/blobdiff_plain/21c32d80b6f505db545840be21030ddbeef9224e..eaa337f176b086a9ebd91884c0b9d9a96772aeb3:/README.md?ds=sidebyside diff --git a/README.md b/README.md index cef3283..ed9f105 100644 --- a/README.md +++ b/README.md @@ -1,553 +1,718 @@ -![Black Logo](https://raw.githubusercontent.com/ambv/black/master/docs/_static/logo2-readme.png) +![Black Logo](https://raw.githubusercontent.com/psf/black/master/docs/_static/logo2-readme.png) +

The Uncompromising Code Formatter

-Build Status -Documentation Status -Coverage Status -License: MIT -PyPI -Code style: black +Build Status +Actions Status +Actions Status +Documentation Status +Coverage Status +License: MIT +PyPI +Downloads +conda-forge +Code style: black

> “Any color you like.” +_Black_ is the uncompromising Python code formatter. By using it, you agree to cede +control over minutiae of hand-formatting. In return, _Black_ gives you speed, +determinism, and freedom from `pycodestyle` nagging about formatting. You will save time +and mental energy for more important matters. + +Blackened code looks the same regardless of the project you're reading. Formatting +becomes transparent after a while and you can focus on the content instead. -*Black* is the uncompromising Python code formatter. By using it, you -agree to cease control over minutiae of hand-formatting. In return, -*Black* gives you speed, determinism, and freedom from `pycodestyle` -nagging about formatting. You will save time and mental energy for -more important matters. +_Black_ makes code review faster by producing the smallest diffs possible. -Blackened code looks the same regardless of the project you're reading. -Formatting becomes transparent after a while and you can focus on the -content instead. +Try it out now using the [Black Playground](https://black.now.sh). Watch the +[PyCon 2019 talk](https://youtu.be/esZLCuWs_2Y) to learn more. -*Black* makes code review faster by producing the smallest diffs -possible. +--- +_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)** -## Installation and Usage +--- + +## Installation and usage ### Installation -*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. +_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 +If you can't wait for the latest _hotness_ and want to install from GitHub, use: + +`pip install git+git://github.com/psf/black` ### Usage To get started right away with sensible defaults: -``` +```sh black {source_file_or_directory} ``` -### Command line options - -Black doesn't provide many options. You can list them by running -`black --help`: +You can run _Black_ as a package if running it as a script doesn't work: -```text -black [OPTIONS] [SRC]... - -Options: - -l, --line-length INTEGER Where to wrap around. [default: 88] - --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. +```sh +python -m black {source_file_or_directory} ``` -*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). - +### Command line options -### NOTE: This is an early pre-release +_Black_ doesn't provide many options. You can list them by running `black --help`: -*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**. +```text +Usage: black [OPTIONS] [SRC]... -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 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. +``` -## The *Black* code style +_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 -recognizes [YAPF](https://github.com/google/yapf)'s block comments to -the same effect, as a courtesy for straddling code. +- 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 -### How *Black* wraps lines +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. -*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. The coding style used by *Black* can be -viewed as a strict subset of PEP 8. +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). -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: +### Migrating your code style without ruining git blame -l = [1, - 2, - 3, -] +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. -# out: +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. -l = [1, 2, 3] ``` - -If not, *Black* will look at the contents of the first outer matching -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()] -] +# Migrate code style to Black +5b4ab991dede475d393e9d69ec388fd6bd949699 ``` -If that still doesn't fit the bill, it will decompose the internal -expression further using the same rule, indenting matching brackets -every time. If the contents of the matching brackets pair are -comma-separated (like an argument list, or a dict literal, and so on) -then *Black* will first try to keep them on the same line with the -matching brackets. If that doesn't work, it will put all of them in -separate lines. -```py3 -# in: - -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, -): - """Applies `variables` to the `template` and writes to `file`.""" - with open(file, "w") as f: - ... -``` +Afterwards, you can pass that file to `git blame` and see clean and meaningful blame +information. -You might have noticed that closing brackets are always dedented and -that a trailing comma is always added. Such formatting produces smaller -diffs; when you add or remove an element, it's always just one line. -Also, having the closing bracket dedented provides a clear delimiter -between two distinct sections of the code that otherwise share the same -indentation level (like the arguments list and the docstring in the -example above). - - -### Line length - -You probably noticed the peculiar default line length. *Black* defaults -to 88 characters per line, which happens to be 10% over 80. This number -was found to produce significantly shorter files than sticking with 80 -(the most popular), or even 79 (used by the standard library). In -general, [90-ish seems like the wise choice](https://youtu.be/wf-BqAjZb8M?t=260). - -If you're paid by the line of code you write, you can pass -`--line-length` with a lower number. *Black* will try to respect that. -However, sometimes it won't be able to without breaking other rules. In -those rare cases, auto-formatted code will exceed your allotted limit. - -You can also increase it, but remember that people with sight disabilities -find it harder to work with line lengths exceeding 100 characters. -It also adversely affects side-by-side diff review on typical screen -resolutions. Long lines also make it harder to present code neatly -in documentation or talk slides. - -If you're using Flake8, you can bump `max-line-length` to 88 and forget -about it. Alternatively, use [Bugbear](https://github.com/PyCQA/flake8-bugbear)'s -B950 warning instead of E501 and keep the max line length at 80 which -you are probably already using. You'd do it like this: -```ini -[flake8] -max-line-length = 80 -... -select = C,E,F,W,B,B950 -ignore = E501 +```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) ``` -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 -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". - - -### 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. - -### 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. - - -## 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. +You can even configure `git` to automatically ignore revisions listed in a file on every +call to `git blame`. -Configuration: -* `g:black_fast` (defaults to `0`) -* `g:black_linelength` (defaults to `88`) -* `g:black_virtualenv` (defaults to `~/.vim/black`) +```console +$ git config blame.ignoreRevsFile .git-blame-ignore-revs +``` -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. +**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!) -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. +### NOTE: This is a beta product -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. +_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. -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. +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`. -**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. +## The _Black_ code style +_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). -### Visual Studio Code +Please refer to this document before submitting an issue. What seems like a bug might be +intended behaviour. -Use [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode). +## 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. -### Other editors +Please refer to this document before submitting an issue just like with the document +above. What seems like a bug might be intended behaviour. -Atom/Nuclide integration is planned by the author, others will -require external contributions. +## pyproject.toml -Patches welcome! ✨ 🍰 ✨ +_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. -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. +**Pro-tip**: If you're asking yourself "Do I need to configure anything?" the answer is +"No". _Black_ is all about sensible defaults. -This can be used for example with PyCharm's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html). +### 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. -## Testimonials +### Where _Black_ looks for the file -**Dusty Phillips**, [writer](https://smile.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=dusty+phillips): +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. -> Black is opinionated so you don't have to be. +If you're formatting standard input, _Black_ will look for configuration starting from +the current working directory. -**Hynek Schlawack**, [creator of `attrs`](http://www.attrs.org/), core -developer of Twisted and CPython: +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: -> An auto-formatter that doesn't suck is all I want for Xmas! +- Windows: `~\.black` +- Unix-like (Linux, MacOS, etc.): `$XDG_CONFIG_HOME/black` (`~/.config/black` if the + `XDG_CONFIG_HOME` environment variable is not set) -**Carl Meyer**, [Django](https://www.djangoproject.com/) core developer: +Note that these are paths to the TOML file itself (meaning that they shouldn't be named +as `pyproject.toml`), not directories where you store the configuration. Here, `~` +refers to the path to your home directory. On Windows, this will be something like +`C:\\Users\UserName`. -> At least the name is good. +You can also explicitly specify the path to a particular file that you want with +`--config`. In this situation _Black_ will not look for any other file. -**Kenneth Reitz**, creator of [`requests`](http://python-requests.org/) -and [`pipenv`](https://docs.pipenv.org/): +If you're running with `--verbose`, you will see a blue message if a file was found and +used. -> This vastly improves the formatting of our code. Thanks a ton! +Please note `blackd` will not use `pyproject.toml` configuration. +### Configuration format -## Show your style +As the file extension suggests, `pyproject.toml` is a +[TOML](https://github.com/toml-lang/toml) file. It contains separate sections for +different tools. _Black_ is using the `[tool.black]` section. The option keys are the +same as long names of options on the command line. + +Note that you have to use single-quoted strings in TOML for regular expressions. It's +the equivalent of r-strings in Python. Multiline strings are treated as verbose regular +expressions by Black. Use `[ ]` to denote a significant space character. -Use the badge in your project's README.md: +
+Example pyproject.toml -```markdown -[![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black) +```toml +[tool.black] +line-length = 88 +target-version = ['py37'] +include = '\.pyi?$' +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) +''' ``` -Looks like this: [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black) +
+### Lookup hierarchy -## License - -MIT - +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. -## Contributing to Black +_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. -In terms of inspiration, *Black* is about as configurable as *gofmt* and -*rustfmt* are. This is deliberate. - -Bug reports and fixes are always welcome! However, before you suggest a -new feature or configuration knob, ask yourself why you want it. If it -enables better integration with some workflow, fixes an inconsistency, -speeds things up, and so on - go for it! On the other hand, if your -answer is "because I don't like a particular formatting" then you're not -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). +## 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). -## Change Log +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). -### 18.4a1 +## blackd -* added `--quiet` (#78) +`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. -### 18.4a0 +## black-primer -* added `--diff` (#87) +`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. -* add line breaks before all delimiters, except in cases like commas, to - better comply with PEP 8 (#73) +(A PR adding Mercurial support will be accepted.) -* standardize string literals to use double quotes (almost) everywhere - (#75) +## Version control integration -* 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) +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: -* fixed 18.3a4 regression: don't crash and burn on empty lines with - trailing whitespace (#80) +```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+ +``` -* fixed 18.3a4 regression: `# yapf: disable` usage as trailing comment - would cause Black to not emit the rest of the file (#95) +Then run `pre-commit install` and you're ready to go. -* when CTRL+C is pressed while formatting many files, Black no longer - freaks out with a flurry of asyncio-related exceptions +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. -* only allow up to two empty lines on module level and only single empty - lines within functions (#74) +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. +## GitHub Actions -### 18.3a4 +Create a file named `.github/workflows/black.yml` inside your repository with: -* `# fmt: off` and `# fmt: on` are implemented (#5) +```yaml +name: Lint -* automatic detection of deprecated Python 2 forms of print statements - and exec statements in the formatted file (#49) +on: [push, pull_request] -* use proper spaces for complex expressions in default values of typed - function arguments (#60) +jobs: + lint: + runs-on: ubuntu-latest + steps: + - uses: actions/checkout@v2 + - uses: actions/setup-python@v2 + - uses: psf/black@stable + with: + args: ". --check" +``` -* only return exit code 1 when --check is used (#50) +### Inputs -* don't remove single trailing commas from square bracket indexing - (#59) +#### `black_args` -* don't omit whitespace if the previous factor leaf wasn't a math - operator (#55) +**optional**: Black input arguments. Defaults to `. --check --diff`. -* omit extra space in kwarg unpacking if it's the first argument (#46) +## Ignoring unmodified files -* omit extra space in [Sphinx auto-attribute comments](http://www.sphinx-doc.org/en/stable/ext/autodoc.html#directive-autoattribute) - (#68) +_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\\AppData\Local\black\black\Cache\\cache...pickle` +- macOS: + `/Users//Library/Caches/black//cache...pickle` +- Linux: + `/home//.cache/black//cache...pickle` -### 18.3a3 +`file-mode` is an int flag that determines whether the file was formatted as 3.6+ only, +as .pyi, and whether string normalization was omitted. -* don't remove single empty lines outside of bracketed expressions - (#19) +To override the location of these files on macOS or Linux, set the environment variable +`XDG_CACHE_HOME` to your preferred location. For example, if you want to put the cache +in the directory you're running _Black_ from, set `XDG_CACHE_HOME=.cache`. _Black_ will +then write the above files to `.cache/black//`. -* added ability to pipe formatting from stdin to stdin (#25) +## Used by -* restored ability to format code with legacy usage of `async` as - a name (#20, #42) +The following notable open-source projects trust _Black_ with enforcing a consistent +code style: pytest, tox, Pyramid, Django Channels, Hypothesis, attrs, SQLAlchemy, +Poetry, PyPA applications (Warehouse, Bandersnatch, Pipenv, virtualenv), pandas, Pillow, +every Datadog Agent Integration, Home Assistant, Zulip. -* even better handling of numpy-style array indexing (#33, again) +The following organizations use _Black_: Facebook, Dropbox, Mozilla, Quora. +Are we missing anyone? Let us know. -### 18.3a2 +## Testimonials -* 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) +**Dusty Phillips**, +[writer](https://smile.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=dusty+phillips): -* ignore empty bracket pairs while splitting. This avoids very weirdly - looking formattings (#34, #35) +> _Black_ is opinionated so you don't have to be. -* remove a trailing comma if there is a single argument to a call +**Hynek Schlawack**, [creator of `attrs`](https://www.attrs.org/), core developer of +Twisted and CPython: -* if top level functions were separated by a comment, don't put four - empty lines after the upper function +> An auto-formatter that doesn't suck is all I want for Xmas! -* fixed unstable formatting of newlines with imports +**Carl Meyer**, [Django](https://www.djangoproject.com/) core developer: -* fixed unintentional folding of post scriptum standalone comments - into last statement if it was a simple statement (#18, #28) +> At least the name is good. -* fixed missing space in numpy-style array indexing (#33) +**Kenneth Reitz**, creator of [`requests`](http://python-requests.org/) and +[`pipenv`](https://readthedocs.org/projects/pipenv/): -* fixed spurious space after star-based unary expressions (#31) +> This vastly improves the formatting of our code. Thanks a ton! +## Show your style -### 18.3a1 +Use the badge in your project's README.md: -* added `--check` +```md +[![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black) +``` -* 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) +Using the badge in README.rst: -* fixed invalid spacing of dots in relative imports (#6, #13) +``` +.. image:: https://img.shields.io/badge/code%20style-black-000000.svg + :target: https://github.com/psf/black +``` -* fixed invalid splitting after comma on unpacked variables in for-loops - (#23) +Looks like this: +[![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black) -* fixed spurious space in parenthesized set expressions (#7) +## License -* fixed spurious space after opening parentheses and in default - arguments (#14, #17) +MIT -* fixed spurious space after unary operators when the operand was - a complex expression (#15) +## Contributing to _Black_ +In terms of inspiration, _Black_ is about as configurable as _gofmt_. This is +deliberate. -### 18.3a0 +Bug reports and fixes are always welcome! However, before you suggest a new feature or +configuration knob, ask yourself why you want it. If it enables better integration with +some workflow, fixes an inconsistency, speeds things up, and so on - go for it! On the +other hand, if your answer is "because I don't like a particular formatting" then you're +not ready to embrace _Black_ yet. Such changes are unlikely to get accepted. You can +still try but prepare to be disappointed. -* first published version, Happy 🍰 Day 2018! +More details can be found in +[CONTRIBUTING](https://github.com/psf/black/blob/master/CONTRIBUTING.md). -* alpha quality +## Change log -* date-versioned (see: https://calver.org/) +The log's become rather long. It moved to its own file. +See [CHANGES](https://github.com/psf/black/blob/master/CHANGES.md). ## 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). +Maintained with [Carol Willing](mailto:carolcode@willingconsulting.com), +[Carl Meyer](mailto:carl@oddbird.net), +[Jelle Zijlstra](mailto:jelle.zijlstra@gmail.com), +[Mika Naylor](mailto:mail@autophagy.io), +[Zsolt Dollenstein](mailto:zsol.zsol@gmail.com), and +[Cooper Lees](mailto:me@cooperlees.com). Multiple contributions by: -* [Artem Malyshev](mailto:proofit404@gmail.com) -* [Daniel M. 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