X-Git-Url: https://git.madduck.net/etc/vim.git/blobdiff_plain/c3589afa3d7d7c1030c1dd1a500fa7efadebd511..4a065a43e1f641a8c5e9266d77feba810e8905ac:/README.md?ds=inline diff --git a/README.md b/README.md index 45cd8f6..20f6fa4 100644 --- a/README.md +++ b/README.md @@ -5,6 +5,7 @@

Build Status Actions Status +Actions Status Documentation Status Coverage Status License: MIT @@ -31,12 +32,14 @@ Try it out now using the [Black Playground](https://black.now.sh). Watch the --- _Contents:_ **[Installation and usage](#installation-and-usage)** | -**[Code style](#the-black-code-style)** | **[pyproject.toml](#pyprojecttoml)** | -**[Editor integration](#editor-integration)** | **[blackd](#blackd)** | +**[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)** | +**[Contributing](#contributing-to-black)** | **[Change log](#change-log)** | **[Authors](#authors)** --- @@ -48,49 +51,66 @@ _Contents:_ **[Installation and usage](#installation-and-usage)** | _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. +#### 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} ``` +You can run _Black_ as a package if running it as a script doesn't work: + +```sh +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 -black [OPTIONS] [SRC]... +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] 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 + 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 @@ -99,6 +119,7 @@ Options: 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 @@ -106,16 +127,23 @@ Options: directories on all platforms (Windows, too). Exclusions are calculated first, inclusions later. [default: /(\.eggs|\.git|\.hg|\.mypy - _cache|\.nox|\.tox|\.venv|_build|buck- + _cache|\.nox|\.tox|\.venv|\.svn|_build|buck- out|build|dist)/] + + --force-exclude TEXT Like --exclude, but files and directories + matching this regex will be excluded even + when they are passed explicitly as arguments + -q, --quiet Don't emit non-error messages to stderr. - Errors are still emitted, silence those with + 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. + --config FILE Read configuration from FILE path. -h, --help Show this message and exit. ``` @@ -127,367 +155,96 @@ _Black_ is a well-behaved Unix-style command-line tool: - it only outputs messages to users on standard error; - exits with code 0 unless an internal error occurred (or `--check` was used). -### NOTE: This is a beta product - -_Black_ is already [successfully used](#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. - -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`. +### Using _Black_ with other tools -## 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 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. +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. -### How _Black_ wraps lines +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_ ignores previous formatting and applies uniform horizontal and vertical -whitespace to your code. The rules for horizontal whitespace 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. +### Migrating your code style without ruining git blame -As for vertical whitespace, _Black_ tries to render one full expression or simple -statement per line. If this fits the allotted line length, great. +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. -```py3 -# in: +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. -j = [1, - 2, - 3 -] - -# out: - -j = [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: - -ImportantClass.important_method(exc, limit, lookup_lines, capture_locals, extra_argument) - -# out: - -ImportantClass.important_method( - exc, limit, lookup_lines, capture_locals, extra_argument -) +# 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, engine: str, header: bool = True, 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, - engine: str, - header: bool = True, - debug: bool = False, -): - """Applies `variables` to the `template` and writes to `file`.""" - with open(file, "w") as f: - ... -``` - -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). - -If a data structure literal (tuple, list, set, dict) or a line of "from" imports cannot -fit in the allotted length, it's always split into one element per line. This minimizes -diffs as well as enables readers of code to find which commit introduced a particular -entry. This also makes _Black_ compatible with [isort](https://pypi.org/p/isort/) with -the following configuration. +Afterwards, you can pass that file to `git blame` and see clean and meaningful blame +information. -

-A compatible `.isort.cfg` - -``` -[settings] -multi_line_output=3 -include_trailing_comma=True -force_grid_wrap=0 -use_parentheses=True -line_length=88 +```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) ``` -The equivalent command line is: +You can even configure `git` to automatically ignore revisions listed in a file on every +call to `git blame`. -``` -$ isort --multi-line=3 --trailing-comma --force-grid-wrap=0 --use-parentheses --line-width=88 [ file.py ] +```console +$ git config blame.ignoreRevsFile .git-blame-ignore-revs ``` -
- -### 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 = E203, E501, W503 -``` +**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!) -You'll find _Black_'s own .flake8 config file is configured like this. Explanation of -why W503 and E203 are disabled can be found further in this documentation. And 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". +### NOTE: This is a beta product -**If you're looking for a minimal, black-compatible flake8 configuration:** +_Black_ is already [successfully used](#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. -```ini -[flake8] -max-line-length = 88 -extend-ignore = E203 -``` +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`. -### Empty lines +## The _Black_ code style -_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. - -_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. +_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`. `# 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). -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 -and classes. _Black_ will not put empty lines between function/class definitions and -standalone comments that immediately precede the given function/class. +Please refer to this document before submitting an issue. What seems like a bug might be +intended behaviour. -_Black_ will enforce single empty lines between a class-level docstring and the first -following field or method. This conforms to -[PEP 257](https://www.python.org/dev/peps/pep-0257/#multi-line-docstrings). - -_Black_ won't insert empty lines after function docstrings unless that empty line is -required due to an inner function starting immediately after. - -### 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. - -_Black_ also standardizes string prefixes, making them always lowercase. On top of that, -if your code is already Python 3.6+ only or it's using the `unicode_literals` future -import, _Black_ will remove `u` from the string prefix as it is meaningless in those -scenarios. - -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/psf/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](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. - -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. - -If you are adopting _Black_ in a large project with pre-existing string conventions -(like the popular -["single quotes for data, double quotes for human-readable strings"](https://stackoverflow.com/a/56190)), -you can pass `--skip-string-normalization` on the command line. This is meant as an -adoption helper, avoid using this for new projects. - -### Numeric literals - -_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`. - -### 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. - -### Slices - -PEP 8 -[recommends](https://www.python.org/dev/peps/pep-0008/#whitespace-in-expressions-and-statements) -to treat `:` in slices as a binary operator with the lowest priority, and to leave an -equal amount of space on either side, except if a parameter is omitted (e.g. -`ham[1 + 1 :]`). It also states that for extended slices, both `:` operators have to -have the same amount of spacing, except if a parameter is omitted (`ham[1 + 1 ::]`). -_Black_ enforces these rules consistently. - -This behaviour may raise `E203 whitespace before ':'` warnings in style guide -enforcement tools like Flake8. Since `E203` 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 (...)` -- assignments like: - - `target = (...)` - - `target: type = (...)` - - `some, *un, packing = (...)` - - `augmented += (...)` - -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. If there is -only a single delimiter and the expression starts or ends with a bracket, the -parenthesis can also be successfully omitted since the existing bracket pair will -organize the expression neatly anyway. Otherwise, the parentheses are added. - -Please note that _Black_ does not add or remove any additional nested parentheses that -you might want to have for clarity or further code organization. For example those -parentheses are not going to be removed: - -```py3 -return not (this or that) -decision = (maybe.this() and values > 0) or (maybe.that() and values < 0) -``` +## Pragmatism -### Call chains - -Some popular APIs, like ORMs, use call chaining. This API style is known as a -[fluent interface](https://en.wikipedia.org/wiki/Fluent_interface). _Black_ formats -those by treating dots that follow a call or an indexing operation like a very low -priority delimiter. It's easier to show the behavior than to explain it. Look at the -example: - -```py3 -def example(session): - result = ( - session.query(models.Customer.id) - .filter( - models.Customer.account_id == account_id, - models.Customer.email == email_address, - ) - .order_by(models.Customer.id.asc()) - .all() - ) -``` +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. -### Typing stub files - -PEP 484 describes the syntax for type hints in Python. One of the use cases for typing -is providing type annotations for modules which cannot contain them directly (they might -be written in C, or they might be third-party, or their implementation may be overly -dynamic, and so on). - -To solve this, -[stub files with the `.pyi` file extension](https://www.python.org/dev/peps/pep-0484/#stub-files) -can be used to describe typing information for an external module. Those stub files omit -the implementation of classes and functions they describe, instead they only contain the -structure of the file (listing globals, functions, and classes with their members). The -recommended code style for those files is more terse than PEP 8: - -- prefer `...` on the same line as the class/function signature; -- avoid vertical whitespace between consecutive module-level functions, names, or - methods and fields within a single class; -- use a single blank line between top-level class definitions, or none if the classes - are very small. - -_Black_ enforces the above rules. There are additional guidelines for formatting `.pyi` -file that are not enforced yet but might be in a future version of the formatter: - -- all function bodies should be empty (contain `...` instead of the body); -- do not use docstrings; -- prefer `...` over `pass`; -- for arguments with a default, use `...` instead of the actual default; -- avoid using string literals in type annotations, stub files support forward references - natively (like Python 3.7 code with `from __future__ import annotations`); -- use variable annotations instead of type comments, even for stubs that target older - versions of Python; -- for arguments that default to `None`, use `Optional[]` explicitly; -- use `float` instead of `Union[int, float]`. +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 @@ -502,7 +259,7 @@ from a `pyproject.toml` file. This is especially useful for specifying custom [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://poetry.eustace.io/) or +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. @@ -536,7 +293,7 @@ the equivalent of r-strings in Python. Multiline strings are treated as verbose expressions by Black. Use `[ ]` to denote a significant space character.
-Example `pyproject.toml` +Example pyproject.toml ```toml [tool.black] @@ -578,308 +335,31 @@ file hierarchy. ## Editor integration -### Emacs - -Use [proofit404/blacken](https://github.com/proofit404/blacken) or -[Elpy](https://github.com/jorgenschaefer/elpy). - -### PyCharm/IntelliJ IDEA - -1. Install `black`. - -```console -$ pip install black -``` - -2. Locate your `black` installation folder. - -On macOS / Linux / BSD: - -```console -$ which black -/usr/local/bin/black # possible location -``` - -On Windows: - -```console -$ where black -%LocalAppData%\Programs\Python\Python36-32\Scripts\black.exe # possible location -``` - -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: - - Arguments: `"$FilePath$"` +_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). -5. Format the currently opened file by selecting `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 or Settings -> Tools -> File Watchers` and click `+` to add a - new watcher: - - Name: Black - - File type: Python - - Scope: Project Files - - Program: - - Arguments: `$FilePath$` - - Output paths to refresh: `$FilePath$` - - Working directory: `$ProjectFileDir$` - - - Uncheck "Auto-save edited files to trigger the watcher" - -### Wing IDE - -Wing supports black via the OS Commands tool, as explained in the Wing documentation on -[pep8 formatting](https://wingware.com/doc/edit/pep8). The detailed procedure is: - -1. Install `black`. - -```console -$ pip install black -``` - -2. Make sure it runs from the command line, e.g. - -```console -$ black --help -``` - -3. In Wing IDE, activate the **OS Commands** panel and define the command **black** to - execute black on the currently selected file: - -- Use the Tools -> OS Commands menu selection -- click on **+** in **OS Commands** -> New: Command line.. - - Title: black - - Command Line: black %s - - I/O Encoding: Use Default - - Key Binding: F1 - - [x] Raise OS Commands when executed - - [x] Auto-save files before execution - - [x] Line mode - -4. Select a file in the editor and press **F1** , or whatever key binding you selected - in step 3, to reformat the file. - -### Vim - -Commands and shortcuts: - -- `: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_skip_string_normalization` (defaults to `0`) -- `g:black_virtualenv` (defaults to `~/.vim/black` or `~/.local/share/nvim/black`) - -To install with [vim-plug](https://github.com/junegunn/vim-plug): - -``` -Plug 'psf/black' -``` - -or with [Vundle](https://github.com/VundleVim/Vundle.vim): - -``` -Plugin 'psf/black' -``` - -or you can copy the plugin from -[plugin/black.vim](https://github.com/psf/black/tree/master/plugin/black.vim). - -``` -mkdir -p ~/.vim/pack/python/start/black/plugin -curl https://raw.githubusercontent.com/psf/black/master/plugin/black.vim -o ~/.vim/pack/python/start/black/plugin/black.vim -``` - -Let me know if this requires any changes to work with Vim 8's builtin `packadd`, or -Pathogen, 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), create a virtualenv manually and point -`g:black_virtualenv` to it. The plugin will use it. - -To run _Black_ on save, add the following line to `.vimrc` or `init.vim`: - -``` -autocmd BufWritePre *.py execute ':Black' -``` - -To run _Black_ on a key press (e.g. F9 below), add this: - -``` -nnoremap :Black -``` - -**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`. When building Vim from source, -use: `./configure --enable-python3interp=yes`. There's many guides online how to do -this. - -### Visual Studio Code - -Use the -[Python extension](https://marketplace.visualstudio.com/items?itemName=ms-python.python) -([instructions](https://code.visualstudio.com/docs/python/editing#_formatting)). - -### SublimeText 3 - -Use [sublack plugin](https://github.com/jgirardet/sublack). - -### Jupyter Notebook Magic - -Use [blackcellmagic](https://github.com/csurfer/blackcellmagic). - -### Python Language Server - -If your editor supports the [Language Server Protocol](https://langserver.org/) (Atom, -Sublime Text, Visual Studio Code and many more), you can use the -[Python Language Server](https://github.com/palantir/python-language-server) with the -[pyls-black](https://github.com/rupert/pyls-black) plugin. - -### Atom/Nuclide - -Use [python-black](https://atom.io/packages/python-black). - -### Kakoune - -Add the following hook to your kakrc, then run black with `:format`. - -``` -hook global WinSetOption filetype=python %{ - set-option window formatcmd 'black -q -' -} -``` - -### Thonny - -Use [Thonny-black-code-format](https://github.com/Franccisco/thonny-black-code-format). - -### Other editors - -Other editors will require external contributions. - -Patches welcome! ✨ 🍰 ✨ - -Any tool that can pipe code through _Black_ using its stdio mode (just -[use `-` as the file name](https://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 or IntelliJ's -[File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html). +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 +`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. +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. -### Usage - -`blackd` is not packaged alongside _Black_ by default because it has additional -dependencies. You will need to do `pip install black[d]` to install it. - -You can start the server on the default port, binding only to the local interface by -running `blackd`. You will see a single line mentioning the server's version, and the -host and port it's listening on. `blackd` will then print an access log similar to most -web servers on standard output, merged with any exception traces caused by invalid -formatting requests. - -`blackd` provides even less options than _Black_. You can see them by running -`blackd --help`: - -```text -Usage: blackd [OPTIONS] - -Options: - --bind-host TEXT Address to bind the server to. - --bind-port INTEGER Port to listen on - --version Show the version and exit. - -h, --help Show this message and exit. -``` +## black-primer -There is no official blackd client tool (yet!). You can test that blackd is working -using `curl`: +`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. -``` -blackd --bind-port 9090 & # or let blackd choose a port -curl -s -XPOST "localhost:9090" -d "print('valid')" -``` - -### Protocol - -`blackd` only accepts `POST` requests at the `/` path. The body of the request 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). - -The headers controlling how code is formatted are: - -- `X-Line-Length`: corresponds to the `--line-length` command line flag. -- `X-Skip-String-Normalization`: corresponds to the `--skip-string-normalization` - command line flag. If present and its value is not the empty string, no string - normalization will be performed. -- `X-Fast-Or-Safe`: if set to `fast`, `blackd` will act as _Black_ does when 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 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`. -- `X-Diff`: corresponds to the `--diff` command line flag. If present, a diff of the - formats will be output. - -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. - -Apart from the above, `blackd` can produce the following response codes: - -- `HTTP 204`: If the input is already well-formatted. The response body is empty. -- `HTTP 200`: If formatting was needed on the input. The response body contains the - blackened Python code, and the `Content-Type` header is set accordingly. -- `HTTP 400`: If the input contains a syntax error. Details of the error are returned in - the response body. -- `HTTP 500`: If there was any kind of error while trying to format the input. The - response body contains a textual representation of the error. - -The response headers include a `X-Black-Version` header containing the version of -_Black_. +(A PR adding Mercurial support will be accepted.) ## Version control integration @@ -890,10 +370,10 @@ Use [pre-commit](https://pre-commit.com/). Once you ```yaml repos: - repo: https://github.com/psf/black - rev: stable + rev: 19.10b0 # Replace by any tag/version: https://github.com/psf/black/tags hooks: - id: black - language_version: python3.6 + language_version: python3 # Should be a command that runs python3.6+ ``` Then run `pre-commit install` and you're ready to go. @@ -905,9 +385,27 @@ for your project. See _Black_'s own example. If you're already using Python 3.7, switch the `language_version` accordingly. Finally, -`stable` is a tag that is pinned to the latest release on PyPI. If you'd rather run on +`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 + +Create a file named `.github/workflows/black.yml` inside your repository with: + +```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 +``` + ## Ignoring unmodified files _Black_ remembers files it has already formatted, unless the `--diff` flag is used or @@ -934,8 +432,10 @@ then write the above files to `.cache/black//`. 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, Pipenv, virtualenv), pandas, Pillow, every Datadog -Agent Integration, Home Assistant. +Poetry, PyPA applications (Warehouse, Bandersnatch, Pipenv, virtualenv), pandas, Pillow, +every Datadog Agent Integration, Home Assistant. + +The following organizations use _Black_: Facebook, Dropbox, Mozilla, Quora. Are we missing anyone? Let us know. @@ -956,7 +456,7 @@ Twisted and CPython: > At least the name is good. **Kenneth Reitz**, creator of [`requests`](http://python-requests.org/) and -[`pipenv`](https://docs.pipenv.org/): +[`pipenv`](https://readthedocs.org/projects/pipenv/): > This vastly improves the formatting of our code. Thanks a ton! @@ -964,7 +464,7 @@ Twisted and CPython: Use the badge in your project's README.md: -```markdown +```md [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black) ``` @@ -994,13 +494,14 @@ other hand, if your answer is "because I don't like a particular formatting" the 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). +More details can be found in +[CONTRIBUTING](https://github.com/psf/black/blob/master/CONTRIBUTING.md). -## Change Log +## Change log The log's become rather long. It moved to its own file. -See [CHANGES](CHANGES.md). +See [CHANGES](https://github.com/psf/black/blob/master/CHANGES.md). ## Authors @@ -1015,68 +516,172 @@ Maintained with [Carol Willing](mailto:carolcode@willingconsulting.com), Multiple contributions by: -- [Abdur-Rahmaan Janhangeer](mailto:cryptolabour@gmail.com) +- [Abdur-Rahmaan Janhangeer](mailto:arj.python@gmail.com) - [Adam Johnson](mailto:me@adamj.eu) +- [Adam Williamson](mailto:adamw@happyassassin.net) - [Alexander Huynh](mailto:github@grande.coffee) +- [Alex Vandiver](mailto:github@chmrr.net) +- [Allan Simon](mailto:allan.simon@supinfo.com) +- Anders-Petter Ljungquist - [Andrew Thorp](mailto:andrew.thorp.dev@gmail.com) +- [Andrew Zhou](mailto:andrewfzhou@gmail.com) - [Andrey](mailto:dyuuus@yandex.ru) - [Andy Freeland](mailto:andy@andyfreeland.net) - [Anthony Sottile](mailto:asottile@umich.edu) - [Arjaan Buijk](mailto:arjaan.buijk@gmail.com) +- [Arnav Borbornah](mailto:arnavborborah11@gmail.com) - [Artem Malyshev](mailto:proofit404@gmail.com) - [Asger Hautop Drewsen](mailto:asgerdrewsen@gmail.com) - [Augie Fackler](mailto:raf@durin42.com) - [Aviskar KC](mailto:aviskarkc10@gmail.com) +- Batuhan Taşkaya +- [Benjamin Wohlwend](mailto:bw@piquadrat.ch) - [Benjamin Woodruff](mailto:github@benjam.info) +- [Bharat Raghunathan](mailto:bharatraghunthan9767@gmail.com) - [Brandt Bucher](mailto:brandtbucher@gmail.com) +- [Brett Cannon](mailto:brett@python.org) +- [Bryan Bugyi](mailto:bryan.bugyi@rutgers.edu) +- [Bryan Forbes](mailto:bryan@reigndropsfall.net) +- [Calum Lind](mailto:calumlind@gmail.com) +- [Charles](mailto:peacech@gmail.com) - Charles Reid +- [Christian Clauss](mailto:cclauss@bluewin.ch) - [Christian Heimes](mailto:christian@python.org) - [Chuck Wooters](mailto:chuck.wooters@microsoft.com) +- [Chris Rose](mailto:offline@offby1.net) +- Codey Oxley +- [Cong](mailto:congusbongus@gmail.com) - [Cooper Ry Lees](mailto:me@cooperlees.com) +- [Dan Davison](mailto:dandavison7@gmail.com) - [Daniel Hahler](mailto:github@thequod.de) - [Daniel M. 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