Let string splitters respect `East_Asian_Width` property (#3445)

[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 1d1e42e75c85ea06442258e4facf9d11cae84ff0..83f8785cc554bef9fab9d187cb64b20824bfe4ec 100644 (file)
--- a/docs/the_black_code_style/current_style.md
+++ b/docs/the_black_code_style/current_style.md
@@ -2,11 +2,16 @@
 
 ## 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`.
-`# fmt: on/off` have to be on the same level of indentation. It also recognizes
+_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 lines that end with
+`# fmt: skip` or blocks that start with `# fmt: off` and end with `# fmt: on`.
+`# fmt: on/off` must be on the same level of indentation and in the same block, meaning
+no unindents beyond the initial indentation level between them. It also recognizes

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


@@ -18,8 +23,7 @@ running `black --preview`.
 
 _Black_ ignores previous formatting and applies uniform horizontal and vertical
 whitespace to your code. The rules for horizontal whitespace can be summarized as: do
 
 _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.


@@ -81,6 +85,19 @@ def very_important_function(
         ...
 ```
 
         ...
 ```
 

+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](../guides/using_black_with_other_tools.md#isort) with the ready-made `black`
+profile or manual configuration.
+
+You might have noticed that closing brackets are always dedented and that a trailing
+comma is always added. Such formatting produces smaller diffs; when you add or remove an
+element, it's always just one line. Also, having the closing bracket dedented provides a
+clear delimiter 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).
+

 (labels/why-no-backslashes)=
 
 _Black_ prefers parentheses over backslashes, and will remove backslashes if found.
 (labels/why-no-backslashes)=
 
 _Black_ prefers parentheses over backslashes, and will remove backslashes if found.


@@ -123,19 +140,6 @@ If you're reaching for backslashes, that's a clear signal that you can do better
 slightly refactor your code. I hope some of the examples above show you that there are
 many ways in which you can do it.
 
 slightly refactor your code. I hope some of the examples above show you that there are
 many ways in which you can do it.
 

-You might have noticed that closing brackets are always dedented and that a trailing
-comma is always added. Such formatting produces smaller diffs; when you add or remove an
-element, it's always just one line. Also, having the closing bracket dedented provides a
-clear delimiter 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).
-
-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](../guides/using_black_with_other_tools.md#isort) with the ready-made `black`
-profile or manual configuration.
-

 ### Line length
 
 You probably noticed the peculiar default line length. _Black_ defaults to 88 characters
 ### Line length
 
 You probably noticed the peculiar default line length. _Black_ defaults to 88 characters


@@ -190,7 +194,45 @@ that in-function vertical whitespace should only be 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 when they're within
 parenthesized expressions. Since such expressions are always reformatted to fit minimal
 _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.
+space, this whitespace is lost. The other exception is that it will remove any empty
+lines immediately following a statement that introduces a new indentation level.
+
+```python
+# in:
+
+def foo():
+
+    print("All the newlines above me should be deleted!")
+
+
+if condition:
+
+    print("No newline above me!")
+
+    print("There is a newline above me, and that's OK!")
+
+
+class Point:
+
+    x: int
+    y: int
+
+# out:
+
+def foo():
+    print("All the newlines above me should be deleted!")
+
+
+if condition:
+    print("No newline above me!")
+
+    print("There is a newline above me, and that's OK!")
+
+
+class Point:
+    x: int
+    y: int
+```

 
 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
 
 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


@@ -284,6 +326,26 @@ 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


@@ -376,16 +438,16 @@ 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.
+
+### Line endings
+
+_Black_ will normalize line endings (`\n` or `\r\n`) based on the first line ending of
+the file.

 
 ## Pragmatism
 
 
 ## Pragmatism
 


@@ -433,15 +495,15 @@ the latter are treated as true raw strings with no special semantics.
 
 ### AST before and after formatting
 
 
 ### AST before and after formatting
 

-When run with `--safe`, _Black_ checks that the code before and after is semantically
-equivalent. This check is done by comparing the AST of the source with the AST of the
-target. There are three limited cases in which the AST does differ:
+When run with `--safe` (the default), _Black_ checks that the code before and after is
+semantically equivalent. This check is done by comparing the AST of the source with the
+AST of the target. There are three limited cases in which the AST does differ:

 
 1. _Black_ cleans up leading and trailing whitespace of docstrings, re-indenting them if
    needed. It's been one of the most popular user-reported features for the formatter to
    fix whitespace issues with docstrings. While the result is technically an AST
 
 1. _Black_ cleans up leading and trailing whitespace of docstrings, re-indenting them if
    needed. It's been one of the most popular user-reported features for the formatter to
    fix whitespace issues with docstrings. While the result is technically an AST

-   difference, due to the various possibilities of forming docstrings, all realtime use
-   of docstrings that we're aware of sanitizes indentation and leading/trailing
+   difference, due to the various possibilities of forming docstrings, all real-world
+   uses of docstrings that we're aware of sanitize indentation and leading/trailing

    whitespace anyway.
 
 1. _Black_ manages optional parentheses for some statements. In the case of the `del`
    whitespace anyway.
 
 1. _Black_ manages optional parentheses for some statements. In the case of the `del`