Changes default logger used by blib2to3 Driver (#732)

[etc/vim.git] / README.md

diff --git a/README.md b/README.md
index 3f82dbd06ab1804fdf0659e5b1aa10c0e3794b1d..9a566773af569b238d2ed2c3651bc17df44d5c1f 100644 (file)
--- a/README.md
+++ b/README.md
@@ -3,10 +3,11 @@
 
 <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/stable/?badge=stable"><img alt="Documentation Status" src="http://readthedocs.org/projects/black/badge/?version=stable"></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/stable/_static/license.svg"></a>
-<a href="https://pypi.python.org/pypi/black"><img alt="PyPI" src="http://black.readthedocs.io/en/stable/_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.org/project/black/"><img alt="PyPI" src="https://black.readthedocs.io/en/stable/_static/pypi.svg"></a>
+<a href="https://pepy.tech/project/black"><img alt="Downloads" src="https://pepy.tech/badge/black"></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>
 


@@ -26,16 +27,19 @@ 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).
+

 ---
 
 *Contents:* **[Installation and usage](#installation-and-usage)** |
 ---
 
 *Contents:* **[Installation and usage](#installation-and-usage)** |

-**[The *Black* code style](#the-black-code-style)** |
+**[Code style](#the-black-code-style)** |
+**[pyproject.toml](#pyprojecttoml)** |

 **[Editor integration](#editor-integration)** |
 **[Editor integration](#editor-integration)** |

+**[blackd](#blackd)** |

 **[Version control integration](#version-control-integration)** |
 **[Ignoring unmodified files](#ignoring-unmodified-files)** |
 **[Testimonials](#testimonials)** |
 **[Show your style](#show-your-style)** |
 **[Version control integration](#version-control-integration)** |
 **[Ignoring unmodified files](#ignoring-unmodified-files)** |
 **[Testimonials](#testimonials)** |
 **[Show your style](#show-your-style)** |

-**[License](#license)** |

 **[Contributing](#contributing-to-black)** |
 **[Change Log](#change-log)** |
 **[Authors](#authors)**
 **[Contributing](#contributing-to-black)** |
 **[Change Log](#change-log)** |
 **[Authors](#authors)**


@@ -60,50 +64,59 @@ 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 [OPTIONS] [SRC]...
 
 Options:
 `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).
+  -l, --line-length INTEGER       How many characters per line to allow.
+                                  [default: 88]
+  -t, --target-version [py27|py33|py34|py35|py36|py37|py38]
+                                  Python versions that should be supported by
+                                  Black's output. [default: per-file auto-
+                                  detection]
+  --pyi                           Format all input files like typing stubs
+                                  regardless of file extension (useful when
+                                  piping source on standard input).

   -S, --skip-string-normalization
   -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.
-  --help                      Show this message and exit.
+                                  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.  An empty value means
+                                  all files are included regardless of the
+                                  name.  Use forward slashes for directories
+                                  on all platforms (Windows, too).  Exclusions
+                                  are calculated first, inclusions later.
+                                  [default: \.pyi?$]
+  --exclude TEXT                  A regular expression that matches files and
+                                  directories that should be excluded on
+                                  recursive searches.  An empty value means no
+                                  paths are excluded. Use forward slashes for
+                                  directories on all platforms (Windows, too).
+                                  Exclusions are calculated first, inclusions
+                                  later.  [default: /(\.eggs|\.git|\.hg|\.mypy
+                                  _cache|\.nox|\.tox|\.venv|_build|buck-
+                                  out|build|dist)/]
+  -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.
+  -h, --help                      Show this message and exit.

 ```
 
 *Black* is a well-behaved Unix-style command-line tool:
 ```
 
 *Black* is a well-behaved Unix-style command-line tool:


@@ -136,7 +149,8 @@ original.  This slows it down.  If you're feeling confident, use
 
 *Black* reformats entire files in place.  It is not configurable.  It
 doesn't take previous formatting into account.  It doesn't reformat
 
 *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
+blocks that start with `# fmt: off` and end with `# fmt: on`. `# fmt: on/off`
+have to be on the same level of indentation. It also

 recognizes [YAPF](https://github.com/google/yapf)'s block comments to
 the same effect, as a courtesy for straddling code.
 
 recognizes [YAPF](https://github.com/google/yapf)'s block comments to
 the same effect, as a courtesy for straddling code.
 


@@ -170,12 +184,12 @@ brackets and put that in a separate indented line.
 ```py3
 # in:
 
 ```py3
 # in:
 

-TracebackException.from_exception(exc, limit, lookup_lines, capture_locals)
+ImportantClass.important_method(exc, limit, lookup_lines, capture_locals, extra_argument)

 
 # out:
 
 
 # out:
 

-TracebackException.from_exception(
-    exc, limit, lookup_lines, capture_locals
+ImportantClass.important_method(
+    exc, limit, lookup_lines, capture_locals, extra_argument

 )
 ```
 
 )
 ```
 


@@ -189,7 +203,7 @@ separate lines.
 ```py3
 # in:
 
 ```py3
 # in:
 

-def very_important_function(template: str, *variables, file: os.PathLike, debug: bool = False):
+def very_important_function(template: str, *variables, file: os.PathLike, engine: str, header: bool = True, debug: bool = False):

     """Applies `variables` to the `template` and writes to `file`."""
     with open(file, 'w') as f:
         ...
     """Applies `variables` to the `template` and writes to `file`."""
     with open(file, 'w') as f:
         ...


@@ -200,6 +214,8 @@ def very_important_function(
     template: str,
     *variables,
     file: os.PathLike,
     template: str,
     *variables,
     file: os.PathLike,

+    engine: str,
+    header: bool = True,

     debug: bool = False,
 ):
     """Applies `variables` to the `template` and writes to `file`."""
     debug: bool = False,
 ):
     """Applies `variables` to the `template` and writes to `file`."""


@@ -230,13 +246,13 @@ the following configuration.
 multi_line_output=3
 include_trailing_comma=True
 force_grid_wrap=0
 multi_line_output=3
 include_trailing_comma=True
 force_grid_wrap=0

-combine_as_imports=True
+use_parentheses=True

 line_length=88
 ```
 
 The equivalent command line is:
 ```
 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 ]
+$ isort --multi-line=3 --trailing-comma --force-grid-wrap=0 --use-parentheses --line-width=88 [ file.py ]

 ```
 </details>
 
 ```
 </details>
 


@@ -272,7 +288,8 @@ ignore = E501
 ```
 
 You'll find *Black*'s own .flake8 config file is configured like this.
 ```
 
 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
+If you're curious about the reasoning behind B950, 
+[Bugbear's documentation](https://github.com/PyCQA/flake8-bugbear#opinionated-warnings)

 explains it.  The tl;dr is "it's like highway speed limits, we won't
 bother you if you overdo it by a few km/h".
 
 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".
 


@@ -350,8 +367,8 @@ 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
 [#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
+text.  They match the docstring standard described in [PEP 257](https://www.python.org/dev/peps/pep-0257/#what-is-a-docstring).
+An empty string in double quotes (`""`) is impossible to confuse with

 a one double-quote regardless of fonts and syntax highlighting used.
 On top of this, double quotes for strings are consistent with C which
 Python interacts a lot with.
 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.


@@ -367,6 +384,13 @@ 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.
 
 pass `--skip-string-normalization` on the command line.  This is meant as
 an adoption helper, avoid using this for new projects.
 

+### Numeric literals
+
+*Black* standardizes most numeric literals to use lowercase letters for the
+syntactic parts and uppercase letters for the digits themselves: `0xAB`
+instead of `0XAB` and `1e10` instead of `1E10`. Python 2 long literals are
+styled as `2L` instead of `2l` to avoid confusion between `l` and `1`.
+

 
 ### Line breaks & binary operators
 
 
 ### Line breaks & binary operators
 


@@ -487,6 +511,102 @@ a future version of the formatter:
 * use `float` instead of `Union[int, float]`.
 
 
 * 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.
+
+Please note `blackd` will not use `pyproject.toml` configuration.
+
+
+### 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
+target_version = ['py37']
+include = '\.pyi?$'
+exclude = '''
+
+(
+  /(
+      \.eggs         # exclude a few common directories in the
+    | \.git          # root of the project
+    | \.hg
+    | \.mypy_cache
+    | \.tox
+    | \.venv
+    | _build
+    | buck-out
+    | build
+    | dist
+  )/
+  | foo.py           # also separately exclude a file named foo.py in
+                     # the root of the project
+)
+'''
+```
+
+</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
 
 ### Emacs
 ## Editor integration
 
 ### Emacs


@@ -524,17 +644,29 @@ $ where black
     - Name: Black
     - Description: Black is the uncompromising Python code formatter.
     - Program: <install_location_from_step_2>
     - Name: Black
     - Description: Black is the uncompromising Python code formatter.
     - Program: <install_location_from_step_2>

-    - Arguments: $FilePath$
+    - 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`.
 
 
 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: <install_location_from_step_2>
+        - Arguments: `$FilePath$`
+        - Output paths to refresh: `$FilePathRelativeToProjectRoot$`
+        - Working directory: `$ProjectFileDir$`
+       - Uncheck "Auto-save edited files to trigger the watcher"

 
 ### Vim
 
 Commands and shortcuts:
 
 
 ### Vim
 
 Commands and shortcuts:
 

-* `,=` or `:Black` to format the entire file (ranges not supported);
+* `: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.
 * `:BlackUpgrade` to upgrade *Black* inside the virtualenv;
 * `:BlackVersion` to get the current version of *Black* inside the
   virtualenv.


@@ -542,12 +674,13 @@ 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`)
 
 To install with [vim-plug](https://github.com/junegunn/vim-plug):
 
 ```
 * `g:black_virtualenv` (defaults to `~/.vim/black`)
 
 To install with [vim-plug](https://github.com/junegunn/vim-plug):
 
 ```

-Plug 'ambv/black',
+Plug 'ambv/black'

 ```
 
 or with [Vundle](https://github.com/VundleVim/Vundle.vim):
 ```
 
 or with [Vundle](https://github.com/VundleVim/Vundle.vim):


@@ -576,7 +709,7 @@ The plugin will use it.
 To run *Black* on save, add the following line to `.vimrc` or `init.vim`:
 
 ```
 To run *Black* on save, add the following line to `.vimrc` or `init.vim`:
 
 ```

-autocmd BufWritePost *.py execute ':Black'
+autocmd BufWritePre *.py execute ':Black'

 ```
 
 **How to get Vim with Python 3.6?**
 ```
 
 **How to get Vim with Python 3.6?**


@@ -589,7 +722,8 @@ 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
 
 
 ### SublimeText 3


@@ -597,26 +731,109 @@ Use [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName
 Use [sublack plugin](https://github.com/jgirardet/sublack).
 
 
 Use [sublack plugin](https://github.com/jgirardet/sublack).
 
 

-### IPython Notebook Magic
+### Jupyter Notebook Magic

 
 Use [blackcellmagic](https://github.com/csurfer/blackcellmagic).
 
 
 
 Use [blackcellmagic](https://github.com/csurfer/blackcellmagic).
 
 

+### Python Language Server
+
+If your editor supports the [Language Server Protocol](https://langserver.org/)
+(Atom, Sublime Text, Visual Studio Code and many more), you can use
+the [Python Language Server](https://github.com/palantir/python-language-server) with the
+[pyls-black](https://github.com/rupert/pyls-black) plugin.
+
+
+### Atom/Nuclide
+
+Use [python-black](https://atom.io/packages/python-black).
+
+

 ### Other editors
 
 ### Other editors
 

-Atom/Nuclide integration is planned by the author, others will
-require external contributions.
+Other editors will 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.
 
 This can be used for example with PyCharm's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html).
 
 The formatted code will be returned on stdout (unless `--check` was
 passed).  *Black* will still emit messages on stderr but that shouldn't
 affect your use case.
 
 This can be used for example with PyCharm's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html).
 

+## blackd
+
+`blackd` is a small HTTP server that exposes *Black*'s functionality over
+a simple protocol. The main benefit of using it is to avoid paying the
+cost of starting up a new *Black* process every time you want to blacken
+a file.
+
+### Usage
+
+`blackd` is not packaged alongside *Black* by default because it has additional
+dependencies. You will need to do `pip install black[d]` to install it.
+
+You can start the server on the default port, binding only to the local interface
+by running `blackd`. You will see a single line mentioning the server's version,
+and the host and port it's listening on. `blackd` will then print an access log
+similar to most web servers on standard output, merged with any exception traces
+caused by invalid formatting requests.
+
+`blackd` provides even less options than *Black*. You can see them by running
+`blackd --help`:
+
+```text
+Usage: blackd [OPTIONS]
+
+Options:
+  --bind-host TEXT                Address to bind the server to.
+  --bind-port INTEGER             Port to listen on
+  --version                       Show the version and exit.
+  -h, --help                      Show this message and exit.
+```
+
+### Protocol
+
+`blackd` only accepts `POST` requests at the `/` path. The body of the request
+should contain the python source code to be formatted, encoded
+according to the `charset` field in the `Content-Type` request header. If no
+`charset` is specified, `blackd` assumes `UTF-8`.
+
+There are a few HTTP headers that control how the source is formatted. These
+correspond to command line flags for *Black*. There is one exception to this:
+`X-Protocol-Version` which if present, should have the value `1`, otherwise the
+request is rejected with `HTTP 501` (Not Implemented).
+
+The headers controlling how code is formatted are:
+
+ - `X-Line-Length`: corresponds to the `--line-length` command line flag.
+ - `X-Skip-String-Normalization`: corresponds to the `--skip-string-normalization`
+    command line flag. If present and its value is not the empty string, no string
+    normalization will be performed.
+ - `X-Fast-Or-Safe`: if set to `fast`, `blackd` will act as *Black* does when
+    passed the `--fast` command line flag.
+ - `X-Python-Variant`: if set to `pyi`, `blackd` will act as *Black* does when
+    passed the `--pyi` command line flag. Otherwise, its value must correspond to
+    a Python version or a set of comma-separated Python versions, optionally
+    prefixed with `py`. For example, to request code that is compatible
+    with Python 3.5 and 3.6, set the header to `py3.5,py3.6`.
+
+If any of these headers are set to invalid values, `blackd` returns a `HTTP 400`
+error response, mentioning the name of the problematic header in the message body.
+
+Apart from the above, `blackd` can produce the following response codes:
+
+ - `HTTP 204`: If the input is already well-formatted. The response body is
+       empty.
+ - `HTTP 200`: If formatting was needed on the input. The response body
+       contains the blackened Python code, and the `Content-Type` header is set
+       accordingly.
+ - `HTTP 400`: If the input contains a syntax error. Details of the error are
+       returned in the response body.
+ - `HTTP 500`: If there was any kind of error while trying to format the input.
+       The response body contains a textual representation of the error.

 
 ## Version control integration
 
 
 ## Version control integration
 


@@ -629,38 +846,43 @@ repos:
     rev: stable
     hooks:
     - id: black
     rev: stable
     hooks:
     - id: black

-      args: [--line-length=88, --safe]

       language_version: python3.6
 ```
 Then run `pre-commit install` and you're ready to go.
 
       language_version: python3.6
 ```
 Then run `pre-commit install` and you're ready to go.
 

-`args` in the above config is optional but shows you how you can change
-the line length if you really need to.  If you're already using Python
-3.7, switch the `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.
+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
 
 
 ## 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
+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:
 
 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`
+* Windows: `C:\\Users\<username>\AppData\Local\black\black\Cache\<version>\cache.<line-length>.<file-mode>.pickle`
+* macOS: `/Users/<username>/Library/Caches/black/<version>/cache.<line-length>.<file-mode>.pickle`
+* Linux: `/home/<username>/.cache/black/<version>/cache.<line-length>.<file-mode>.pickle`
+
+`file-mode` is an int flag that determines whether the file was formatted as 3.6+ only,
+as .pyi, and whether string normalization was omitted.

 
 
 ## 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
+**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!
 developer of Twisted and CPython:
 
 > An auto-formatter that doesn't suck is all I want for Xmas!


@@ -683,6 +905,12 @@ 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)
 
 


@@ -691,7 +919,7 @@ 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*.
 This is deliberate.
 
 In terms of inspiration, *Black* is about as configurable as *gofmt*.
 This is deliberate.


@@ -709,6 +937,111 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 
 ## Change Log
 
 
 ## Change Log
 

+### 19.2b0
+
+* removed `--py36` (use `--target-version=py36` instead) (#724)
+
+* long `del` statements are now split into multiple lines (#698)
+
+* *Black* no longer normalizes numeric literals to include `_` separators (#696)
+
+* new option `--target-version` to control which Python versions
+  *Black*-formatted code should target (#618)
+
+### 18.9b0
+
+* numeric literals are now formatted by *Black* (#452, #461, #464, #469):
+
+  * numeric literals are normalized to include `_` separators on Python 3.6+ code
+
+  * added `--skip-numeric-underscore-normalization` to disable the above behavior and
+    leave numeric underscores as they were in the input
+
+  * code with `_` in numeric literals is recognized as Python 3.6+
+
+  * most letters in numeric literals are lowercased (e.g., in `1e10`, `0x01`)
+
+  * hexadecimal digits are always uppercased (e.g. `0xBADC0DE`)
+
+* added `blackd`, see [its documentation](#blackd) for more info (#349)
+
+* adjacent string literals are now correctly split into multiple lines (#463)
+
+* trailing comma is now added to single imports that don't fit on a line (#250)
+
+* cache is now populated when `--check` is successful for a file which speeds up
+  consecutive checks of properly formatted unmodified files (#448)
+
+* whitespace at the beginning of the file is now removed (#399)
+
+* fixed mangling [pweave](http://mpastell.com/pweave/) and
+  [Spyder IDE](https://pythonhosted.org/spyder/) special comments (#532)
+
+* fixed unstable formatting when unpacking big tuples (#267)
+
+* fixed parsing of `__future__` imports with renames (#389)
+
+* fixed scope of `# fmt: off` when directly preceding `yield` and other nodes (#385)
+
+* fixed formatting of lambda expressions with default arguments (#468)
+
+* fixed ``async for`` statements: *Black* no longer breaks them into separate
+  lines (#372)
+
+* note: the Vim plugin stopped registering ``,=`` as a default chord as it turned out
+  to be a bad idea (#415)
+
+
+### 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)
 ### 18.6b1
 
 * hotfix: don't output human-facing information on stdout (#299)


@@ -840,10 +1173,10 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 * generalized star expression handling, including double stars; this
   fixes multiplication making expressions "unsafe" for trailing commas (#132)
 
 * 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
+* *Black* no longer enforces putting empty lines behind control flow statements

   (#90)
 
   (#90)
 

-* Black now splits imports like "Mode 3 + trailing comma" of isort (#127)
+* *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 comment indentation when a standalone comment closes a block (#16, #32)
 


@@ -896,16 +1229,16 @@ 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


@@ -952,7 +1285,7 @@ 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


@@ -1011,6 +1344,7 @@ Glued together by [Łukasz Langa](mailto:lukasz@langa.pl).
 
 Maintained with [Carol Willing](mailto:carolcode@willingconsulting.com),
 [Carl Meyer](mailto:carl@oddbird.net),
 
 Maintained with [Carol Willing](mailto:carolcode@willingconsulting.com),
 [Carl Meyer](mailto:carl@oddbird.net),

+[Jelle Zijlstra](mailto:jelle.zijlstra@gmail.com),

 [Mika Naylor](mailto:mail@autophagy.io), and
 [Zsolt Dollenstein](mailto:zsol.zsol@gmail.com).
 
 [Mika Naylor](mailto:mail@autophagy.io), and
 [Zsolt Dollenstein](mailto:zsol.zsol@gmail.com).
 


@@ -1019,30 +1353,17 @@ Multiple contributions by:
 * [Artem Malyshev](mailto:proofit404@gmail.com)
 * [Christian Heimes](mailto:christian@python.org)
 * [Daniel M. Capella](mailto:polycitizen@gmail.com)
 * [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)
+* [Eli Treuherz](mailto:eli@treuherz.com)

 * Hugo van Kemenade
 * [Ivan Katanić](mailto:ivan.katanic@gmail.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)
 * [Jonas Obrist](mailto:ojiidotch@gmail.com)
 * [Luka Sterbic](mailto:luka.sterbic@gmail.com)
 * [Miguel Gaiowski](mailto:miggaiowski@gmail.com)

+* [Miroslav Shubernetskiy](mailto:miroslav@miki725.com)
+* [Neraste](mailto:neraste.herr10@gmail.com)

 * [Osaetin Daniel](mailto:osaetindaniel@gmail.com)
 * [Osaetin Daniel](mailto:osaetindaniel@gmail.com)

-* [Peter Bengtsson](mailto:peterbe@mozilla.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)
 * [Stavros Korokithakis](mailto:hi@stavros.io)
 * [Sunil Kapil](mailto:snlkapil@gmail.com)
 * [Vishwas B Sharma](mailto:sharma.vishwas88@gmail.com)

-
----
-
-*Contents:*
-**[Installation and Usage](#installation-and-usage)** |
-**[The *Black* code style](#the-black-code-style)** |
-**[Editor integration](#editor-integration)** |
-**[Version control integration](#version-control-integration)** |
-**[Ignoring unmodified files](#ignoring-unmodified-files)** |
-**[Testimonials](#testimonials)** |
-**[Show your style](#show-your-style)** |
-**[License](#license)** |
-**[Contributing](#contributing-to-black)** |
-**[Change Log](#change-log)** |
-**[Authors](#authors)**
+* [Chuck Wooters](mailto:chuck.wooters@microsoft.com)