Move imports of `ThreadPoolExecutor` into `reformat_many()`, allowing Black-in-the...

[etc/vim.git] / docs / the_black_code_style / current_style.md

diff --git a/docs/the_black_code_style/current_style.md b/docs/the_black_code_style/current_style.md
index 00001dbc461cebd03837216ca6b8f6e7d113294b..d54c7abaf5d57da6602a13bf2006342eaf1e5a81 100644 (file)
--- a/docs/the_black_code_style/current_style.md
+++ b/docs/the_black_code_style/current_style.md
@@ -2,20 +2,27 @@
 
 ## Code style
 
 
 ## Code style
 

-_Black_ reformats entire files in place. Style configuration options are deliberately
-limited and rarely added. It doesn't take previous formatting into account, except for
-the magic trailing comma and preserving newlines. It doesn't reformat blocks that start
-with `# fmt: off` and end with `# fmt: on`, or lines that ends with `# fmt: skip`.
+_Black_ aims for consistency, generality, readability and reducing git diffs. Similar
+language constructs are formatted with similar rules. Style configuration options are
+deliberately limited and rarely added. Previous formatting is taken into account as
+little as possible, with rare exceptions like the magic trailing comma. The coding style
+used by _Black_ can be viewed as a strict subset of PEP 8.
+
+_Black_ reformats entire files in place. It doesn't reformat blocks that start with
+`# fmt: off` and end with `# fmt: on`, or lines that ends with `# fmt: skip`.

 `# 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.
 
 `# 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.
 

+The rest of this document describes the current formatting style. If you're interested
+in trying out where the style is heading, see [future style](./future_style.md) and try
+running `black --preview`.
+

 ### How _Black_ wraps lines
 
 _Black_ ignores previous formatting and applies uniform horizontal and vertical
 whitespace to your code. The rules for horizontal whitespace can be summarized as: do
 ### How _Black_ wraps lines
 
 _Black_ ignores previous formatting and applies uniform horizontal and vertical
 whitespace to your code. The rules for horizontal whitespace can be summarized as: do

-whatever makes `pycodestyle` happy. The coding style used by _Black_ can be viewed as a
-strict subset of PEP 8.
+whatever makes `pycodestyle` happy.

 
 As for vertical whitespace, _Black_ tries to render one full expression or simple
 statement per line. If this fits the allotted line length, great.
 
 As for vertical whitespace, _Black_ tries to render one full expression or simple
 statement per line. If this fits the allotted line length, great.


@@ -200,6 +207,16 @@ following field or method. This conforms to
 _Black_ won't insert empty lines after function docstrings unless that empty line is
 required due to an inner function starting immediately after.
 
 _Black_ won't insert empty lines after function docstrings unless that empty line is
 required due to an inner function starting immediately after.
 

+### Comments
+
+_Black_ does not format comment contents, but it enforces two spaces between code and a
+comment on the same line, and a space before the comment text begins. Some types of
+comments that require specific spacing rules are respected: doc comments (`#: comment`),
+section comments with long runs of hashes, and Spyder cells. Non-breaking spaces after
+hashes are also preserved. Comments may sometimes be moved because of formatting
+changes, which can break tools that assign special meaning to them. See
+[AST before and after formatting](#ast-before-and-after-formatting) for more discussion.
+

 ### Trailing commas
 
 _Black_ will add trailing commas to expressions that are split by comma where each
 ### Trailing commas
 
 _Black_ will add trailing commas to expressions that are split by comma where each


@@ -223,10 +240,10 @@ _Black_ prefers double quotes (`"` and `"""`) over single quotes (`'` and `'''`)
 will replace the latter with the former as long as it does not result in more backslash
 escapes than before.
 
 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.
+_Black_ also standardizes string prefixes. Prefix characters are made lowercase with the
+exception of [capital "R" prefixes](#rstrings-and-rstrings), unicode literal markers
+(`u`) are removed because they are meaningless in Python 3, and in the case of multiple
+characters "r" is put first as in spoken language: "raw f-string".

 
 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
 
 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


@@ -250,27 +267,18 @@ If you are adopting _Black_ in a large project with pre-existing string conventi
 you can pass `--skip-string-normalization` on the command line. This is meant as an
 adoption helper, avoid using this for new projects.
 
 you can pass `--skip-string-normalization` on the command line. This is meant as an
 adoption helper, avoid using this for new projects.
 

-As an experimental option (can be enabled by `--experimental-string-processing`),
-_Black_ splits long strings (using parentheses where appropriate) and merges short ones.
-When split, parts of f-strings that don't need formatting are converted to plain
-strings. User-made splits are respected when they do not exceed the line length limit.
-Line continuation backslashes are converted into parenthesized strings. Unnecessary
-parentheses are stripped. Because the functionality is experimental, feedback and issue
-reports are highly encouraged!
-

 _Black_ also processes docstrings. Firstly the indentation of docstrings is corrected
 for both quotations and the text within, although relative indentation in the text is
 preserved. Superfluous trailing whitespace on each line and unnecessary new lines at the
 end of the docstring are removed. All leading tabs are converted to spaces, but tabs
 inside text are preserved. Whitespace leading and trailing one-line docstrings is
 _Black_ also processes docstrings. Firstly the indentation of docstrings is corrected
 for both quotations and the text within, although relative indentation in the text is
 preserved. Superfluous trailing whitespace on each line and unnecessary new lines at the
 end of the docstring are removed. All leading tabs are converted to spaces, but tabs
 inside text are preserved. Whitespace leading and trailing one-line docstrings is

-removed. The quotations of an empty docstring are separated with one space.
+removed.

 
 ### 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
 
 ### 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`.
+`1e10` instead of `1E10`.

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


@@ -279,6 +287,26 @@ multiple lines. This is so that _Black_ is compliant with the recent changes in
 [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.
 
 [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.
 

+Almost all operators will be surrounded by single spaces, the only exceptions are unary
+operators (`+`, `-`, and `~`), and power operators when both operands are simple. For
+powers, an operand is considered simple if it's only a NAME, numeric CONSTANT, or
+attribute access (chained attribute access is allowed), with or without a preceding
+unary operator.
+
+```python
+# For example, these won't be surrounded by whitespace
+a = x**y
+b = config.base**5.2
+c = config.base**runtime.config.exponent
+d = 2**5
+e = 2**~5
+
+# ... but these will be surrounded by whitespace
+f = 2 ** get_exponent()
+g = get_x() ** get_y()
+h = config['base'] ** 2
+```
+

 ### Slices
 
 PEP 8
 ### Slices
 
 PEP 8


@@ -371,16 +399,11 @@ recommended code style for those files is more terse than PEP 8:
 _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:
 
 _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`;
 - 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
 - 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]`.
+  versions of Python.

 
 ## Pragmatism
 
 
 ## Pragmatism