X-Git-Url: https://git.madduck.net/etc/vim.git/blobdiff_plain/3fb451687293c993b10d860449eb405ddd44f377..a18ee4018f855007bf4a23027a8d6478e56a36bf:/README.md?ds=inline
diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -1,46 +1,37 @@
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+
The Uncompromising Code Formatter
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> âAny color you like.â
+_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.
-*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.
+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* makes code review faster by producing the smallest diffs
-possible.
+_Black_ makes code review faster by producing the smallest diffs possible.
-Try it out now using the [Black Playground](https://black.now.sh).
+Try it out now using the [Black Playground](https://black.vercel.app). Watch the
+[PyCon 2019 talk](https://youtu.be/esZLCuWs_2Y) to learn more.
---
-*Contents:* **[Installation and usage](#installation-and-usage)** |
-**[Code style](#the-black-code-style)** |
-**[pyproject.toml](#pyprojecttoml)** |
-**[Editor integration](#editor-integration)** |
-**[Version control integration](#version-control-integration)** |
-**[Ignoring unmodified files](#ignoring-unmodified-files)** |
-**[Testimonials](#testimonials)** |
-**[Show your style](#show-your-style)** |
-**[Contributing](#contributing-to-black)** |
-**[Change Log](#change-log)** |
-**[Authors](#authors)**
+**[Read the documentation on ReadTheDocs!](https://black.readthedocs.io/en/stable)**
---
@@ -48,742 +39,125 @@ Try it out now using the [Black Playground](https://black.now.sh).
### 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]`. If you want to format Jupyter Notebooks, install with
+`pip install black[jupyter]`.
+
+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`:
-
-```text
-black [OPTIONS] [SRC]...
-
-Options:
- -l, --line-length INTEGER Where to wrap around. [default: 88]
- --py36 Allow using Python 3.6-only syntax on all input
- files. This will put trailing commas in function
- signatures and calls also after *args and
- **kwargs. [default: per-file auto-detection]
- --pyi Format all input files like typing stubs
- regardless of file extension (useful when piping
- source on standard input).
- -S, --skip-string-normalization
- Don't normalize string quotes or prefixes.
- --check Don't write the files back, just return the
- status. Return code 0 means nothing would
- change. Return code 1 means some files would be
- reformatted. Return code 123 means there was an
- internal error.
- --diff Don't write the files back, just output a diff
- for each file on stdout.
- --fast / --safe If --fast given, skip temporary sanity checks.
- [default: --safe]
- --include TEXT A regular expression that matches files and
- directories that should be included on
- recursive searches. On Windows, use forward
- slashes for directories. [default: \.pyi?$]
- --exclude TEXT A regular expression that matches files and
- directories that should be excluded on
- recursive searches. On Windows, use forward
- slashes for directories. [default:
- build/|buck-out/|dist/|_build/|\.git/|\.hg/|
- \.mypy_cache/|\.tox/|\.venv/]
- -q, --quiet Don't emit non-error messages to stderr. Errors
- are still emitted, silence those with
- 2>/dev/null.
- -v, --verbose Also emit messages to stderr about files
- that were not changed or were ignored due to
- --exclude=.
- --version Show the version and exit.
- --config PATH Read configuration from PATH.
- --help Show this message and exit.
-```
-
-*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 occurred (or `--check` was
- used).
-
-
-### NOTE: This is a beta product
-
-*Black* is already successfully used by several 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``.
-
-
-## 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`. It also
-recognizes [YAPF](https://github.com/google/yapf)'s block comments to
-the same effect, as a courtesy for straddling code.
-
-
-### How *Black* wraps lines
-
-*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.
-
-As for vertical whitespace, *Black* tries to render one full expression
-or simple statement per line. If this fits the allotted line length,
-great.
-```py3
-# in:
-
-l = [1,
- 2,
- 3,
-]
-
-# out:
-
-l = [1, 2, 3]
-```
-
-If not, *Black* will look at the contents of the first outer matching
-brackets and put that in a separate indented line.
-```py3
-# in:
-
-TracebackException.from_exception(exc, limit, lookup_lines, capture_locals)
-
-# out:
-
-TracebackException.from_exception(
- exc, limit, lookup_lines, capture_locals
-)
-```
-
-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:
- ...
-```
-
-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.
-
-
-A compatible `.isort.cfg`
-
-```
-[settings]
-multi_line_output=3
-include_trailing_comma=True
-force_grid_wrap=0
-combine_as_imports=True
-line_length=88
-```
-
-The equivalent command line is:
-```
-$ isort --multi-line=3 --trailing-comma --force-grid-wrap=0 --combine-as --line-width=88 [ file.py ]
-```
-
-
-### 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
-```
-
-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.
-
-*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 and classes. *Black* will not put empty
-lines between function/class definitions and standalone comments that
-immediately precede the given function/class.
-
-*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.
+You can run _Black_ as a package if running it as a script doesn't work:
-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/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.
-
-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.
-
-
-### 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)
+```sh
+python -m black {source_file_or_directory}
```
+Further information can be found in our docs:
-### 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()
- )
-```
-
-
-### 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]`.
-
-
-## pyproject.toml
-
-*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`
-patterns for your project.
-
-**Pro-tip**: If you're asking yourself "Do I need to configure anything?"
-the answer is "No". *Black* is all about sensible defaults.
-
-
-### 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://poetry.eustace.io/) or
-[Flit](https://flit.readthedocs.io/en/latest/) it can fully replace the
-need for `setup.py` and `setup.cfg` files.
-
-
-### Where *Black* looks for the file
-
-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.
-
-If you're formatting standard input, *Black* will look for configuration
-starting from the current working directory.
-
-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.
-
-If you're running with `--verbose`, you will see a blue message if
-a file was found and used.
-
-
-### Configuration format
-
-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.
-
-
-Example `pyproject.toml`
-
-```toml
-[tool.black]
-line-length = 88
-py36 = true
-include = '\.pyi?$'
-exclude = '''
-/(
- \.git
- | \.hg
- | \.mypy_cache
- | \.tox
- | \.venv
- | _build
- | buck-out
- | build
- | dist
-
- # The following are specific to Black, you probably don't want those.
- | blib2to3
- | tests/data
-)/
-'''
-```
-
-
-
-### Lookup hierarchy
-
-Command-line options have defaults that you can see in `--help`.
-A `pyproject.toml` can override those defaults. Finally, options
-provided by the user on the command line override both.
-
-*Black* will only ever use one `pyproject.toml` file during an entire
-run. It doesn't look for multiple files, and doesn't compose
-configuration from different levels of the file hierarchy.
-
-
-## Editor integration
-
-### Emacs
-
-Use [proofit404/blacken](https://github.com/proofit404/blacken).
-
-
-### PyCharm
-
-1. Install `black`.
-
-```console
-$ 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 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:
- - Arguments: `$FilePath$`
-
-5. Format the currently opened file by selecting `Tools -> External Tools -> black`.
- - Alternatively, you can set a keyboard shortcut by navigating to `Preferences -> Keymap -> External Tools -> External Tools - Black`.
-
-6. Optionally, run Black on every file save:
-
- 1. Make sure you have the [File Watcher](https://plugins.jetbrains.com/plugin/7177-file-watchers) plugin installed.
- 2. Go to `Preferences -> Tools -> File Watchers` and click `+` to add a new watcher:
- - Name: Black
- - File type: Python
- - Scope: Project Files
- - Program:
- - Arguments: `$FilePath$`
- - Output paths to refresh: `$FilePathRelativeToProjectRoot$`
- - Working directory: `$ProjectFileDir$`
-
-### 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`)
-
-To install with [vim-plug](https://github.com/junegunn/vim-plug):
-
-```
-Plug 'ambv/black',
-```
-
-or with [Vundle](https://github.com/VundleVim/Vundle.vim):
-
-```
-Plugin 'ambv/black'
-```
-
-or you can copy the plugin from [plugin/black.vim](https://github.com/ambv/black/tree/master/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'
-```
-
-**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 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).
+- [Usage and Configuration](https://black.readthedocs.io/en/stable/usage_and_configuration/index.html)
+### NOTE: This is a beta product
-### IPython Notebook Magic
+_Black_ is already [successfully used](https://github.com/psf/black#used-by) by many
+projects, small and big. Black has a comprehensive test suite, with efficient parallel
+tests, and our own auto formatting and parallel Continuous Integration runner. However,
+_Black_ is still beta. 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.
-Use [blackcellmagic](https://github.com/csurfer/blackcellmagic).
+Also, as a safety measure which slows down processing, _Black_ will check that the
+reformatted code still produces a valid AST that is effectively equivalent to the
+original (see the
+[Pragmatism](https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#ast-before-and-after-formatting)
+section for details). If you're feeling confident, use `--fast`.
+## The _Black_ code style
-### Python Language Server
+_Black_ is a PEP 8 compliant opinionated formatter. _Black_ reformats entire files in
+place. Style configuration options are deliberately limited and rarely added. It doesn't
+take previous formatting into account (see [Pragmatism](#pragmatism) for exceptions).
-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.
+Our documentation covers the current _Black_ code style, but planned changes to it are
+also documented. They're both worth taking a look:
+- [The _Black_ Code Style: Current style](https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html)
+- [The _Black_ Code Style: Future style](https://black.readthedocs.io/en/stable/the_black_code_style/future_style.html)
-### Atom/Nuclide
+Please refer to this document before submitting an issue. What seems like a bug might be
+intended behaviour.
-Use [atom-black](https://github.com/hauntsaninja/atom-black).
+### 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.
-### Other editors
+- [The _Black_ code style: Pragmatism](https://black.readthedocs.io/en/stable/the_black_code_style/current_style.html#pragmatism)
-Other editors will require external contributions.
+Please refer to this document before submitting an issue just like with the document
+above. What seems like a bug might be intended behaviour.
-Patches welcome! ⨠ð° â¨
+## Configuration
-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.
+_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`/`--force-exclude`/`--extend-exclude` patterns for your
+project.
-This can be used for example with PyCharm's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html).
+You can find more details in our documentation:
+- [The basics: Configuration via a file](https://black.readthedocs.io/en/stable/usage_and_configuration/the_basics.html#configuration-via-a-file)
-## Version control integration
+And if you're looking for more general configuration documentation:
-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
- language_version: python3.6
-```
-Then run `pre-commit install` and you're ready to go.
+- [Usage and Configuration](https://black.readthedocs.io/en/stable/usage_and_configuration/index.html)
-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`
-for an example.
+**Pro-tip**: If you're asking yourself "Do I need to configure anything?" the answer is
+"No". _Black_ is all about sensible defaults. Applying those defaults will have your
+code in compliance with many other _Black_ formatted projects.
-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 master, this is also an option.
+## Used by
+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,
+Twisted, LocalStack, every Datadog Agent Integration, Home Assistant, Zulip, Kedro, and
+many more.
-## Ignoring unmodified files
+The following organizations use _Black_: Facebook, Dropbox, KeepTruckin, Mozilla, Quora,
+Duolingo, QuantumBlack, Tesla.
-*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:
+Are we missing anyone? Let us know.
-* Windows: `C:\\Users\\AppData\Local\black\black\Cache\\cache..pickle`
-* macOS: `/Users//Library/Caches/black//cache..pickle`
-* Linux: `/home//.cache/black//cache..pickle`
+## Testimonials
+**Mike Bayer**, [author of `SQLAlchemy`](https://www.sqlalchemy.org/):
-## Testimonials
+> I can't think of any single tool in my entire programming career that has given me a
+> bigger productivity increase by its introduction. I can now do refactorings in about
+> 1% of the keystrokes that it would have taken me previously when we had no way for
+> code to format itself.
-**Dusty Phillips**, [writer](https://smile.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=dusty+phillips):
+**Dusty Phillips**,
+[writer](https://smile.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=dusty+phillips):
-> *Black* is opinionated so you don't have to be.
+> _Black_ is opinionated so you don't have to be.
-**Hynek Schlawack**, [creator of `attrs`](http://www.attrs.org/), core
-developer of Twisted and CPython:
+**Hynek Schlawack**, [creator of `attrs`](https://www.attrs.org/), core developer of
+Twisted and CPython:
> An auto-formatter that doesn't suck is all I want for Xmas!
@@ -791,427 +165,66 @@ developer of Twisted and CPython:
> At least the name is good.
-**Kenneth Reitz**, creator of [`requests`](http://python-requests.org/)
-and [`pipenv`](https://docs.pipenv.org/):
+**Kenneth Reitz**, creator of [`requests`](http://python-requests.org/) and
+[`pipenv`](https://readthedocs.org/projects/pipenv/):
> This vastly improves the formatting of our code. Thanks a ton!
-
## Show your style
Use the badge in your project's README.md:
-```markdown
-[](https://github.com/ambv/black)
+```md
+[](https://github.com/psf/black)
```
Using the badge in README.rst:
+
```
.. image:: https://img.shields.io/badge/code%20style-black-000000.svg
- :target: https://github.com/ambv/black
+ :target: https://github.com/psf/black
```
-Looks like this: [](https://github.com/ambv/black)
-
+Looks like this:
+[](https://github.com/psf/black)
## License
MIT
+## Contributing
-## Contributing to *Black*
-
-In terms of inspiration, *Black* is about as configurable as *gofmt*.
-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).
-
-
-## Change Log
-
-### 18.8b0
-
-* fix parsing of `__future__` imports with renames (#389)
-* fix scope of `# fmt: off` when directly preceding `yield` and other nodes (#385)
-
-### 18.6b4
-
-* hotfix: don't freeze when multiple comments directly precede `# fmt: off` (#371)
-
-
-### 18.6b3
-
-* typing stub files (`.pyi`) now have blank lines added after constants (#340)
-
-* `# fmt: off` and `# fmt: on` are now much more dependable:
-
- * they now work also within bracket pairs (#329)
-
- * they now correctly work across function/class boundaries (#335)
-
- * they now work when an indentation block starts with empty lines or misaligned
- comments (#334)
-
-* made Click not fail on invalid environments; note that Click is right but the
- likelihood we'll need to access non-ASCII file paths when dealing with Python source
- code is low (#277)
+Welcome! Happy to see you willing to make the project better. You can get started by
+reading this:
-* fixed improper formatting of f-strings with quotes inside interpolated
- expressions (#322)
+- [Contributing: The basics](https://black.readthedocs.io/en/latest/contributing/the_basics.html)
-* fixed unnecessary slowdown when long list literals where found in a file
+You can also take a look at the rest of the contributing docs or talk with the
+developers:
-* fixed unnecessary slowdown on AST nodes with very many siblings
+- [Contributing documentation](https://black.readthedocs.io/en/latest/contributing/index.html)
+- [Chat on Discord](https://discord.gg/RtVdv86PrH)
-* fixed cannibalizing backslashes during string normalization
+## Change log
-* fixed a crash due to symbolic links pointing outside of the project directory (#338)
+The log has become rather long. It moved to its own file.
+See [CHANGES](https://black.readthedocs.io/en/latest/change_log.html).
-### 18.6b2
-
-* added `--config` (#65)
-
-* added `-h` equivalent to `--help` (#316)
-
-* fixed improper unmodified file caching when `-S` was used
-
-* fixed extra space in string unpacking (#305)
-
-* fixed formatting of empty triple quoted strings (#313)
-
-* fixed unnecessary slowdown in comment placement calculation on lines without
- comments
-
-
-### 18.6b1
-
-* hotfix: don't output human-facing information on stdout (#299)
-
-* hotfix: don't output cake emoji on non-zero return code (#300)
-
-
-### 18.6b0
-
-* added `--include` and `--exclude` (#270)
-
-* added `--skip-string-normalization` (#118)
-
-* added `--verbose` (#283)
-
-* the header output in `--diff` now actually conforms to the unified diff spec
-
-* fixed long trivial assignments being wrapped in unnecessary parentheses (#273)
-
-* fixed unnecessary parentheses when a line contained multiline strings (#232)
-
-* fixed stdin handling not working correctly if an old version of Click was
- used (#276)
-
-* *Black* now preserves line endings when formatting a file in place (#258)
-
-
-### 18.5b1
-
-* added `--pyi` (#249)
-
-* added `--py36` (#249)
-
-* Python grammar pickle caches are stored with the formatting caches, making
- *Black* work in environments where site-packages is not user-writable (#192)
-
-* *Black* now enforces a PEP 257 empty line after a class-level docstring
- (and/or fields) and the first method
-
-* fixed invalid code produced when standalone comments were present in a trailer
- that was omitted from line splitting on a large expression (#237)
-
-* fixed optional parentheses being removed within `# fmt: off` sections (#224)
-
-* fixed invalid code produced when stars in very long imports were incorrectly
- wrapped in optional parentheses (#234)
-
-* fixed unstable formatting when inline comments were moved around in
- a trailer that was omitted from line splitting on a large expression
- (#238)
-
-* fixed extra empty line between a class declaration and the first
- method if no class docstring or fields are present (#219)
-
-* fixed extra empty line between a function signature and an inner
- function or inner class (#196)
-
-
-### 18.5b0
-
-* call chains are now formatted according to the
- [fluent interfaces](https://en.wikipedia.org/wiki/Fluent_interface)
- style (#67)
-
-* data structure literals (tuples, lists, dictionaries, and sets) are
- now also always exploded like imports when they don't fit in a single
- line (#152)
-
-* slices are now formatted according to PEP 8 (#178)
-
-* parentheses are now also managed automatically on the right-hand side
- of assignments and return statements (#140)
-
-* math operators now use their respective priorities for delimiting multiline
- expressions (#148)
-
-* optional parentheses are now omitted on expressions that start or end
- with a bracket and only contain a single operator (#177)
-
-* empty parentheses in a class definition are now removed (#145, #180)
-
-* string prefixes are now standardized to lowercase and `u` is removed
- on Python 3.6+ only code and Python 2.7+ code with the `unicode_literals`
- future import (#188, #198, #199)
-
-* typing stub files (`.pyi`) are now formatted in a style that is consistent
- with PEP 484 (#207, #210)
-
-* progress when reformatting many files is now reported incrementally
-
-* fixed trailers (content with brackets) being unnecessarily exploded
- into their own lines after a dedented closing bracket (#119)
-
-* fixed an invalid trailing comma sometimes left in imports (#185)
-
-* fixed non-deterministic formatting when multiple pairs of removable parentheses
- were used (#183)
-
-* fixed multiline strings being unnecessarily wrapped in optional
- parentheses in long assignments (#215)
-
-* fixed not splitting long from-imports with only a single name
-
-* fixed Python 3.6+ file discovery by also looking at function calls with
- unpacking. This fixed non-deterministic formatting if trailing commas
- where used both in function signatures with stars and function calls
- with stars but the former would be reformatted to a single line.
-
-* fixed crash on dealing with optional parentheses (#193)
-
-* fixed "is", "is not", "in", and "not in" not considered operators for
- splitting purposes
-
-* fixed crash when dead symlinks where encountered
-
-
-### 18.4a4
-
-* don't populate the cache on `--check` (#175)
-
-
-### 18.4a3
-
-* added a "cache"; files already reformatted that haven't changed on disk
- won't be reformatted again (#109)
-
-* `--check` and `--diff` are no longer mutually exclusive (#149)
-
-* generalized star expression handling, including double stars; this
- fixes multiplication making expressions "unsafe" for trailing commas (#132)
-
-* *Black* no longer enforces putting empty lines behind control flow statements
- (#90)
-
-* *Black* now splits imports like "Mode 3 + trailing comma" of isort (#127)
-
-* fixed comment indentation when a standalone comment closes a block (#16, #32)
-
-* fixed standalone comments receiving extra empty lines if immediately preceding
- a class, def, or decorator (#56, #154)
-
-* fixed `--diff` not showing entire path (#130)
-
-* fixed parsing of complex expressions after star and double stars in
- function calls (#2)
-
-* fixed invalid splitting on comma in lambda arguments (#133)
-
-* fixed missing splits of ternary expressions (#141)
-
-
-### 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)
-
-
-### 18.3a4
-
-* `# fmt: off` and `# fmt: on` are implemented (#5)
-
-* automatic detection of deprecated Python 2 forms of print statements
- and exec statements in the formatted file (#49)
-
-* use proper spaces for complex expressions in default values of typed
- function arguments (#60)
-
-* only return exit code 1 when --check is used (#50)
-
-* don't remove single trailing commas from square bracket indexing
- (#59)
-
-* don't omit whitespace if the previous factor leaf wasn't a math
- operator (#55)
-
-* omit extra space in kwarg unpacking if it's the first argument (#46)
-
-* omit extra space in [Sphinx auto-attribute comments](http://www.sphinx-doc.org/en/stable/ext/autodoc.html#directive-autoattribute)
- (#68)
-
-
-### 18.3a3
-
-* don't remove single empty lines outside of bracketed expressions
- (#19)
-
-* added ability to pipe formatting from stdin to stdin (#25)
-
-* restored ability to format code with legacy usage of `async` as
- a name (#20, #42)
-
-* even better handling of numpy-style array indexing (#33, again)
-
-
-### 18.3a2
-
-* changed positioning of binary operators to occur at beginning of lines
- instead of at the end, following [a recent change to PEP 8](https://github.com/python/peps/commit/c59c4376ad233a62ca4b3a6060c81368bd21e85b)
- (#21)
-
-* ignore empty bracket pairs while splitting. This avoids very weirdly
- looking formattings (#34, #35)
-
-* remove a trailing comma if there is a single argument to a call
-
-* if top level functions were separated by a comment, don't put four
- empty lines after the upper function
-
-* fixed unstable formatting of newlines with imports
-
-* fixed unintentional folding of post scriptum standalone comments
- into last statement if it was a simple statement (#18, #28)
-
-* fixed missing space in numpy-style array indexing (#33)
-
-* fixed spurious space after star-based unary expressions (#31)
-
-
-### 18.3a1
-
-* added `--check`
-
-* only put trailing commas in function signatures and calls if it's
- safe to do so. If the file is Python 3.6+ it's always safe, otherwise
- only safe if there are no `*args` or `**kwargs` used in the signature
- or call. (#8)
-
-* fixed invalid spacing of dots in relative imports (#6, #13)
-
-* fixed invalid splitting after comma on unpacked variables in for-loops
- (#23)
-
-* fixed spurious space in parenthesized set expressions (#7)
-
-* fixed spurious space after opening parentheses and in default
- arguments (#14, #17)
-
-* fixed spurious space after unary operators when the operand was
- a complex expression (#15)
-
-
-### 18.3a0
+## Authors
-* first published version, Happy ð° Day 2018!
+The author list is quite long nowadays, so it lives in its own file.
-* alpha quality
+See [AUTHORS.md](./AUTHORS.md)
-* date-versioned (see: https://calver.org/)
+## Code of Conduct
+Everyone participating in the _Black_ project, and in particular in the issue tracker,
+pull requests, and social media activity, is expected to treat other people with respect
+and more generally to follow the guidelines articulated in the
+[Python Community Code of Conduct](https://www.python.org/psf/codeofconduct/).
-## Authors
+At the same time, humor is encouraged. In fact, basic familiarity with Monty Python's
+Flying Circus is expected. We are not savages.
-Glued together by [Åukasz Langa](mailto:lukasz@langa.pl).
-
-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)
-* [Christian Heimes](mailto:christian@python.org)
-* [Daniel M. Capella](mailto:polycitizen@gmail.com)
-* [Eli Treuherz](mailto:eli.treuherz@cgi.com)
-* Hugo van Kemenade
-* [Ivan KataniÄ](mailto:ivan.katanic@gmail.com)
-* [Jelle Zijlstra](mailto:jelle.zijlstra@gmail.com)
-* [Jonas Obrist](mailto:ojiidotch@gmail.com)
-* [Luka Sterbic](mailto:luka.sterbic@gmail.com)
-* [Miguel Gaiowski](mailto:miggaiowski@gmail.com)
-* [Neraste](neraste.herr10@gmail.com)
-* [Osaetin Daniel](mailto:osaetindaniel@gmail.com)
-* [Peter Bengtsson](mailto:mail@peterbe.com)
-* [Stavros Korokithakis](mailto:hi@stavros.io)
-* [Sunil Kapil](mailto:snlkapil@gmail.com)
-* [Vishwas B Sharma](mailto:sharma.vishwas88@gmail.com)
+And if you _really_ need to slap somebody, do it with a fish while dancing.