Re-use indexes of current iteration in `comments_after()`

[etc/vim.git] / README.md

diff --git a/README.md b/README.md
index 1cd1ef0ba4c0ce1a8f2eb11f35c7458727c3297b..3297f8797292aff5ab9e95aaabf289786afed9f6 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="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://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="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"><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.


@@ -53,13 +53,18 @@ 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]

-  --check                     Don't write back the files, just return the
+  --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.
                               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]
   --fast / --safe             If --fast given, skip temporary sanity checks.
                               [default: --safe]

+  -q, --quiet                 Don't emit non-error messages to stderr. Errors
+                              are still emitted, silence those with
+                              2>/dev/null.

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


@@ -69,7 +74,7 @@ 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).
 
 


@@ -101,9 +106,9 @@ 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,


@@ -159,7 +164,7 @@ def very_important_function(
     debug: bool = False,
 ):
     """Applies `variables` to the `template` and writes to `file`."""
     debug: bool = False,
 ):
     """Applies `variables` to the `template` and writes to `file`."""

-    with open(file, 'w') as f:
+    with open(file, "w") as f:

         ...
 ```
 
         ...
 ```
 


@@ -171,6 +176,14 @@ 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 line of "from" imports cannot fit in the allotted length, it's always split
+into one per line.  Imports tend to change often and this minimizes diffs, as well
+as enables readers of code to easily find which commit introduced a particular
+import.  This exception also makes *Black* compatible with
+[isort](https://pypi.org/p/isort/).  Use `multi_line_output=3`,
+`include_trailing_comma=True`, `force_grid_wrap=0`, and `line_length=88` in your
+isort config.
+

 
 ### Line length
 
 
 ### Line length
 


@@ -213,23 +226,18 @@ 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 left by the original editors,
-except when they're added within parenthesized expressions.  Since such
-expressions are always reformatted to fit minimal space, this whitespace
-is lost.
+*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
 
 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.  *Black* will not put empty lines between
+function/class definitions and standalone comments that immediately precede
+the given function/class.

 
 
 ### Trailing commas
 
 
 ### Trailing commas


@@ -260,11 +268,187 @@ 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.
+
+*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.
+
+### 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.  Otherwise, the parentheses are always added.
+

 
 ## Editor integration
 
 
 ## Editor integration
 

-* Visual Studio Code: [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode)
-* Emacs: [proofit404/blacken](https://github.com/proofit404/blacken)
+### Emacs
+
+Use [proofit404/blacken](https://github.com/proofit404/blacken).
+
+
+### PyCharm
+
+1. Install `black`.
+
+        $ pip install black
+
+2. Locate your `black` installation folder.
+
+  On MacOS / Linux / BSD:
+
+        $ which black
+        /usr/local/bin/black  # possible location
+
+  On Windows:
+
+        $ 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: <install_location_from_step_2>
+    - 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`.
+
+
+### Vim
+
+Commands and shortcuts:
+
+* `,=` or `:Black` to format the entire file (ranges not supported);
+* `:BlackUpgrade` to upgrade *Black* inside the virtualenv;
+* `:BlackVersion` to get the current version of *Black* inside the
+  virtualenv.
+
+Configuration:
+* `g:black_fast` (defaults to `0`)
+* `g:black_linelength` (defaults to `88`)
+* `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.
+
+**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 [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode).
+
+### SublimeText 3
+
+Use [sublack plugin](https://github.com/jgirardet/sublack).
+
+### IPython Notebook Magic
+
+Use [blackcellmagic](https://github.com/csurfer/blackcellmagic).
+
+### Other editors
+
+Atom/Nuclide integration is planned by the author, others will
+require external contributions.
+
+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)).
 
 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)).


@@ -272,10 +456,43 @@ 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.
 
 passed).  *Black* will still emit messages on stderr but that shouldn't
 affect your use case.
 

-Vim and Atom/Nuclide integration is planned by the author, others will
-require external contributions.
+This can be used for example with PyCharm's [File Watchers](https://www.jetbrains.com/help/pycharm/file-watchers.html).

 
 

-Patches welcome! ✨ 🍰 ✨
+
+## Version control integration
+
+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
+      args: [--line-length=88, --safe]
+      python_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 `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.
+
+
+## Ignoring non-modified files
+
+*Black* remembers files it 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
 
 
 ## Testimonials


@@ -317,8 +534,8 @@ 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


@@ -333,6 +550,122 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 
 ## Change Log
 
 
 ## Change Log
 

+### 18.5a0 (unreleased)
+
+* 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)
+
+* 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)
+
+* fixed an invalid trailing comma sometimes left in imports (#185)
+
+* fixed non-deterministic formatting when multiple pairs of removable parentheses
+  were used (#183)
+
+* 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.
+
+
+### 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)
 ### 18.3a4
 
 * `# fmt: off` and `# fmt: on` are implemented (#5)


@@ -429,3 +762,22 @@ More details can be found in [CONTRIBUTING](CONTRIBUTING.md).
 ## Authors
 
 Glued together by [Łukasz Langa](mailto:lukasz@langa.pl).
 ## Authors
 
 Glued together by [Łukasz 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 Katanić](mailto:ivan.katanic@gmail.com)
+* [Jelle Zijlstra](mailto:jelle.zijlstra@gmail.com)
+* [Jonas Obrist](mailto:ojiidotch@gmail.com)
+* [Osaetin Daniel](mailto:osaetindaniel@gmail.com)
+* [Sunil Kapil](mailto:snlkapil@gmail.com)
+* [Vishwas B Sharma](mailto:sharma.vishwas88@gmail.com)