Automatic management of parentheses in assignments

[etc/vim.git] / README.md

diff --git a/README.md b/README.md
index 06b732466eb3b305307992f35a23df99cc476956..aca49994cd7f268ad520d41384ed0801f083763e 100644 (file)
--- a/README.md
+++ b/README.md
@@ -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.


@@ -176,6 +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
 


@@ -218,10 +226,7 @@ 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 +235,9 @@ 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


@@ -300,6 +303,19 @@ 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


@@ -311,6 +327,11 @@ 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


@@ -368,9 +389,21 @@ Configuration:
 * `g:black_linelength` (defaults to `88`)
 * `g:black_virtualenv` (defaults to `~/.vim/black`)
 
 * `g:black_linelength` (defaults to `88`)
 * `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


@@ -397,6 +430,9 @@ to do this.
 
 Use [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode).
 
 
 Use [joslarson.black-vscode](https://marketplace.visualstudio.com/items?itemName=joslarson.black-vscode).
 

+### SublimeText 3
+
+Use [sublack plugin](https://github.com/jgirardet/sublack).

 
 ### Other editors
 
 
 ### Other editors
 


@@ -436,6 +472,20 @@ the line length if you really need to.  If you're already using Python
 that is pinned to the latest release on PyPI.  If you'd rather run on
 master, this is also an option.
 
 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
 
 **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):


@@ -475,8 +525,8 @@ 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


@@ -491,6 +541,78 @@ 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)
+
+* 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)
 ### 18.4a1
 
 * added `--quiet` (#78)


@@ -503,6 +625,7 @@ 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)


@@ -635,8 +758,12 @@ 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)

+* [Jonas Obrist](mailto:ojiidotch@gmail.com)

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

+* [Sunil Kapil](mailto:snlkapil@gmail.com)
+* [Vishwas B Sharma](mailto:sharma.vishwas88@gmail.com)