write cache in --check mode (#453)

[etc/vim.git] / README.md

diff --git a/README.md b/README.md
index 06b732466eb3b305307992f35a23df99cc476956..61cb88ae6236c063ff7791c866e299900dfd8dc9 100644 (file)
--- a/README.md
+++ b/README.md
@@ -3,10 +3,10 @@
 
 <p align="center">
 <a href="https://travis-ci.org/ambv/black"><img alt="Build Status" src="https://travis-ci.org/ambv/black.svg?branch=master"></a>
 
 <p align="center">
 <a href="https://travis-ci.org/ambv/black"><img alt="Build Status" src="https://travis-ci.org/ambv/black.svg?branch=master"></a>

-<a href="http://black.readthedocs.io/en/latest/?badge=latest"><img alt="Documentation Status" src="http://readthedocs.org/projects/black/badge/?version=latest"></a>
+<a href="https://black.readthedocs.io/en/stable/?badge=stable"><img alt="Documentation Status" src="https://readthedocs.org/projects/black/badge/?version=stable"></a>

 <a href="https://coveralls.io/github/ambv/black?branch=master"><img alt="Coverage Status" src="https://coveralls.io/repos/github/ambv/black/badge.svg?branch=master"></a>
 <a href="https://coveralls.io/github/ambv/black?branch=master"><img alt="Coverage Status" src="https://coveralls.io/repos/github/ambv/black/badge.svg?branch=master"></a>

-<a href="https://github.com/ambv/black/blob/master/LICENSE"><img alt="License: MIT" src="http://black.readthedocs.io/en/latest/_static/license.svg"></a>
-<a href="https://pypi.python.org/pypi/black"><img alt="PyPI" src="http://black.readthedocs.io/en/latest/_static/pypi.svg"></a>
+<a href="https://github.com/ambv/black/blob/master/LICENSE"><img alt="License: MIT" src="https://black.readthedocs.io/en/stable/_static/license.svg"></a>
+<a href="https://pypi.python.org/pypi/black"><img alt="PyPI" src="https://black.readthedocs.io/en/stable/_static/pypi.svg"></a>

 <a href="https://github.com/ambv/black"><img alt="Code style: black" src="https://img.shields.io/badge/code%20style-black-000000.svg"></a>
 </p>
 
 <a href="https://github.com/ambv/black"><img alt="Code style: black" src="https://img.shields.io/badge/code%20style-black-000000.svg"></a>
 </p>
 


@@ -14,7 +14,7 @@
 
 
 *Black* is the uncompromising Python code formatter.  By using it, you
 
 
 *Black* is the uncompromising Python code formatter.  By using it, you

-agree to cease control over minutiae of hand-formatting.  In return,
+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* gives you speed, determinism, and freedom from `pycodestyle`
 nagging about formatting.  You will save time and mental energy for
 more important matters.


@@ -26,8 +26,23 @@ content instead.
 *Black* makes code review faster by producing the smallest diffs
 possible.
 
 *Black* makes code review faster by producing the smallest diffs
 possible.
 

+---

 
 

-## Installation and Usage
+*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)**
+
+---
+
+## Installation and usage

 
 ### Installation
 
 
 ### Installation
 


@@ -45,7 +60,7 @@ black {source_file_or_directory}
 
 ### Command line options
 
 
 ### Command line options
 

-Black doesn't provide many options.  You can list them by running
+*Black* doesn't provide many options.  You can list them by running

 `black --help`:
 
 ```text
 `black --help`:
 
 ```text


@@ -53,6 +68,15 @@ black [OPTIONS] [SRC]...
 
 Options:
   -l, --line-length INTEGER   Where to wrap around.  [default: 88]
 
 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
   --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


@@ -62,10 +86,24 @@ Options:
                               for each file on stdout.
   --fast / --safe             If --fast given, skip temporary sanity checks.
                               [default: --safe]
                               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.
   -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.
   --version                   Show the version and exit.

+  --config PATH               Read configuration from PATH.

   --help                      Show this message and exit.
 ```
 
   --help                      Show this message and exit.
 ```
 


@@ -74,18 +112,20 @@ Options:
 * 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;
 * 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
+* exits with code 0 unless an internal error occurred (or `--check` was

   used).
 
 
   used).
 
 

-### NOTE: This is an early pre-release
+### NOTE: This is a beta product

 
 

-*Black* can already successfully format itself and the standard library.
+*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
 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.
+"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,
 What this means for you is that **until the formatter becomes stable,

-you should expect some formatting to change in the future**.
+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
 
 Also, as a temporary safety measure, *Black* will check that the
 reformatted code still produces a valid AST that is equivalent to the


@@ -106,9 +146,9 @@ the same effect, as a courtesy for straddling code.
 
 *Black* ignores previous formatting and applies uniform horizontal
 and vertical whitespace to your code.  The rules for horizontal
 
 *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.
+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,
 
 As for vertical whitespace, *Black* tries to render one full expression
 or simple statement per line.  If this fits the allotted line length,


@@ -131,13 +171,13 @@ brackets and put that in a separate indented line.
 ```py3
 # in:
 
 ```py3
 # in:
 

-l = [[n for n in list_bosses()], [n for n in list_employees()]]
+TracebackException.from_exception(exc, limit, lookup_lines, capture_locals)

 
 # out:
 
 
 # out:
 

-l = [
-    [n for n in list_bosses()], [n for n in list_employees()]
-]
+TracebackException.from_exception(
+    exc, limit, lookup_lines, capture_locals
+)

 ```
 
 If that still doesn't fit the bill, it will decompose the internal
 ```
 
 If that still doesn't fit the bill, it will decompose the internal


@@ -176,6 +216,30 @@ 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).
 
 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.
+
+<details>
+<summary>A compatible `.isort.cfg`</summary>
+
+```
+[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 ]
+```
+</details>

 
 ### Line length
 
 
 ### Line length
 


@@ -218,10 +282,7 @@ bother you if you overdo it by a few km/h".
 
 *Black* avoids spurious vertical whitespace.  This is in the spirit of
 PEP 8 which says that in-function vertical whitespace should only be
 
 *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.
+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
 
 *Black* will allow single empty lines inside functions, and single and
 double empty lines on module level left by the original editors, except


@@ -230,11 +291,17 @@ 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
 
 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.
+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
 
 
 ### Trailing commas


@@ -265,12 +332,18 @@ 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.
 
 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.
 
 ### 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
 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


@@ -289,7 +362,14 @@ 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.
 
 key.  My recommendation here is to keep using whatever is faster to type
 and let *Black* handle the transformation.
 

-### Line Breaks & Binary Operators
+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
 
 *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


@@ -300,6 +380,21 @@ 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.
 
 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
 ### Parentheses
 
 Some parentheses are optional in the Python grammar.  Any expression can


@@ -311,10 +406,178 @@ interesting cases:
 - `for (...) in (...):`
 - `assert (...), (...)`
 - `from X import (...)`
 - `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
 
 In those cases, parentheses are removed when the entire statement fits
 in one line, or if the inner expression doesn't have any delimiters to

-further split on.  Otherwise, the parentheses are always added.
+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)
+```
+
+
+### 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.
+
+<details>
+<summary>Example `pyproject.toml`</summary>
+
+```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
+)/
+'''
+```
+
+</details>
+
+### 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
 
 
 ## Editor integration


@@ -328,19 +591,25 @@ Use [proofit404/blacken](https://github.com/proofit404/blacken).
 
 1. Install `black`.
 
 
 1. Install `black`.
 

-        $ pip install black
+```console
+$ pip install black
+```

 
 2. Locate your `black` installation folder.
 
 
 2. Locate your `black` installation folder.
 

-  On MacOS / Linux / BSD:
+  On macOS / Linux / BSD:

 
 

-        $ which black
-        /usr/local/bin/black  # possible location
+```console
+$ which black
+/usr/local/bin/black  # possible location
+```

 
   On Windows:
 
 
   On Windows:
 

-        $ where black
-        %LocalAppData%\Programs\Python\Python36-32\Scripts\black.exe  # possible location
+```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`.
 
 
 3. Open External tools in PyCharm with `File -> Settings -> Tools -> External Tools`.
 


@@ -351,7 +620,7 @@ Use [proofit404/blacken](https://github.com/proofit404/blacken).
     - Arguments: $FilePath$
 
 5. Format the currently opened file by selecting `Tools -> External Tools -> black`.
     - 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`.
+    - Alternatively, you can set a keyboard shortcut by navigating to `Preferences -> Keymap -> External Tools -> External Tools - Black`.

 
 
 ### Vim
 
 
 ### Vim


@@ -366,11 +635,24 @@ Commands and shortcuts:
 Configuration:
 * `g:black_fast` (defaults to `0`)
 * `g:black_linelength` (defaults to `88`)
 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`)
 
 * `g:black_virtualenv` (defaults to `~/.vim/black`)
 

-To install, copy the plugin from [vim/plugin/black.vim](https://github.com/ambv/black/tree/master/vim/plugin/black.vim).
+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
 Let me know if this requires any changes to work with Vim 8's builtin

-`packadd`, or Pathogen, or Vundle, and so on.
+`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
 
 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


@@ -381,13 +663,19 @@ 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
 by calling `:BlackUpgrade` and restarting Vim.
 
 If you need to do anything special to make your virtualenv work and

-install *Black* (for example you want to run a version from master), just
+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.
 
 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.
 **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`.
+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.
 When building Vim from source, use:
 `./configure --enable-python3interp=yes`. There's many guides online how
 to do this.


@@ -395,7 +683,26 @@ to do this.
 
 ### Visual Studio Code
 
 
 ### Visual Studio Code
 

-Use [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode).
+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).
+
+
+### IPython 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.

 
 
 ### Other editors
 
 
 ### Other editors


@@ -406,7 +713,7 @@ require external contributions.
 Patches welcome! ✨ 🍰 ✨
 
 Any tool that can pipe code through *Black* using its stdio mode (just
 Patches welcome! ✨ 🍰 ✨
 
 Any tool that can pipe code through *Black* using its stdio mode (just

-[use `-` as the file name](http://www.tldp.org/LDP/abs/html/special-chars.html#DASHREF2)).
+[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.
 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.


@@ -425,22 +732,38 @@ repos:
     rev: stable
     hooks:
     - id: black
     rev: stable
     hooks:
     - id: black

-      args: [--line-length=88, --safe]
-      python_version: python3.6
+      language_version: python3.6

 ```
 Then run `pre-commit install` and you're ready to go.
 
 ```
 Then run `pre-commit install` and you're ready to go.
 

-`args` in the above config is optional but shows you how you can change
-the line length if you really need to.  If you're already using Python
-3.7, switch the `python_version` accordingly. Finally, `stable` is a tag
-that is pinned to the latest release on PyPI.  If you'd rather run on
-master, this is also an option.
+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.
+
+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.
+
+
+## Ignoring unmodified files
+
+*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\<username>\AppData\Local\black\black\Cache\<version>\cache.<line-length>.pickle`
+* macOS: `/Users/<username>/Library/Caches/black/<version>/cache.<line-length>.pickle`
+* Linux: `/home/<username>/.cache/black/<version>/cache.<line-length>.pickle`
+

 
 ## Testimonials
 
 **Dusty Phillips**, [writer](https://smile.amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=dusty+phillips):
 
 
 ## Testimonials
 
 **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`](http://www.attrs.org/), core
 developer of Twisted and CPython:


@@ -465,6 +788,12 @@ Use the badge in your project's README.md:
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black)
 ```
 
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black)
 ```
 

+Using the badge in README.rst:
+```
+.. image:: https://img.shields.io/badge/code%20style-black-000000.svg
+    :target: https://github.com/ambv/black
+```    
+

 Looks like this: [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black)
 
 
 Looks like this: [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black)
 
 


@@ -473,10 +802,10 @@ Looks like this: [![Code style: black](https://img.shields.io/badge/code%20style
 MIT
 
 
 MIT
 
 

-## Contributing to Black
+## Contributing to *Black*

 
 

-In terms of inspiration, *Black* is about as configurable as *gofmt* and
-*rustfmt* are.  This is deliberate.
+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
 
 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


@@ -491,6 +820,224 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 
 ## Change Log
 
 
 ## 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)
+
+* fixed improper formatting of f-strings with quotes inside interpolated
+  expressions (#322)
+
+* fixed unnecessary slowdown when long list literals where found in a file
+
+* fixed unnecessary slowdown on AST nodes with very many siblings
+
+* fixed cannibalizing backslashes during string normalization
+
+* fixed a crash due to symbolic links pointing outside of the project directory (#338)
+
+
+### 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)
 ### 18.4a1
 
 * added `--quiet` (#78)


@@ -503,6 +1050,7 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 
 * fixed removing backslash escapes from raw strings (#100, #105)
 
 
 * fixed removing backslash escapes from raw strings (#100, #105)
 

+

 ### 18.4a0
 
 * added `--diff` (#87)
 ### 18.4a0
 
 * added `--diff` (#87)


@@ -514,16 +1062,16 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
   (#75)
 
 * fixed handling of standalone comments within nested bracketed
   (#75)
 
 * fixed handling of standalone comments within nested bracketed

-  expressions; Black will no longer produce super long lines or put all
+  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
   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)
+  would cause *Black* to not emit the rest of the file (#95)

 
 

-* when CTRL+C is pressed while formatting many files, Black no longer
+* 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
   freaks out with a flurry of asyncio-related exceptions
 
 * only allow up to two empty lines on module level and only single empty


@@ -570,7 +1118,7 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 ### 18.3a2
 
 * changed positioning of binary operators to occur at beginning of lines
 ### 18.3a2
 
 * changed positioning of binary operators to occur at beginning of lines

-  instead of at the end, following [a recent change to PEP8](https://github.com/python/peps/commit/c59c4376ad233a62ca4b3a6060c81368bd21e85b)
+  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
   (#21)
 
 * ignore empty bracket pairs while splitting. This avoids very weirdly


@@ -635,8 +1183,18 @@ Maintained with [Carol Willing](mailto:carolcode@willingconsulting.com),
 Multiple contributions by:
 * [Anthony Sottile](mailto:asottile@umich.edu)
 * [Artem Malyshev](mailto:proofit404@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 Katanić](mailto:ivan.katanic@gmail.com)
 * [Daniel M. Capella](mailto:polycitizen@gmail.com)
 * [Eli Treuherz](mailto:eli.treuherz@cgi.com)
 * Hugo van Kemenade
 * [Ivan Katanić](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)
 * [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)