X-Git-Url: https://git.madduck.net/etc/vim.git/blobdiff_plain/f7580103407743a317e22297793822dd91f8fefe..1b08cbc63400a8b8e0fbb620b6b2a4dab35e1e7b:/docs/the_black_code_style/future_style.md diff --git a/docs/the_black_code_style/future_style.md b/docs/the_black_code_style/future_style.md index 9ca260f..861bb64 100644 --- a/docs/the_black_code_style/future_style.md +++ b/docs/the_black_code_style/future_style.md @@ -31,8 +31,8 @@ with \ ... # backslashes and an ugly stranded colon ``` -Although when the target version is Python 3.9 or higher, _Black_ will, when we -implement this, use parentheses instead since they're allowed in Python 3.9 and higher. +Although when the target version is Python 3.9 or higher, _Black_ uses parentheses +instead in `--preview` mode (see below) since they're allowed in Python 3.9 and higher. An alternative to consider if the backslashes in the above formatting are undesirable is to use {external:py:obj}`contextlib.ExitStack` to combine context managers in the @@ -47,11 +47,13 @@ with contextlib.ExitStack() as exit_stack: ... ``` +(labels/preview-style)= + ## Preview style Experimental, potentially disruptive style changes are gathered under the `--preview` CLI flag. At the end of each year, these changes may be adopted into the default style, -as described in [The Black Code Style](./index.rst). Because the functionality is +as described in [The Black Code Style](index.md). Because the functionality is experimental, feedback and issue reports are highly encouraged! ### Improved string processing @@ -63,92 +65,98 @@ limit. Line continuation backslashes are converted into parenthesized strings. Unnecessary parentheses are stripped. The stability and status of this feature is tracked in [this issue](https://github.com/psf/black/issues/2188). -### Improved empty line management - -1. _Black_ will remove newlines in the beginning of new code blocks, i.e. when the - indentation level is increased. For example: - - ```python - def my_func(): - - print("The line above me will be deleted!") - ``` - - will be changed to: - - ```python - def my_func(): - print("The line above me will be deleted!") - ``` - - This new feature will be applied to **all code blocks**: `def`, `class`, `if`, - `for`, `while`, `with`, `case` and `match`. - -2. _Black_ will enforce empty lines before classes and functions with leading comments. - For example: +### Improved line breaks - ```python - some_var = 1 - # Leading sticky comment - def my_func(): - ... - ``` +For assignment expressions, _Black_ now prefers to split and wrap the right side of the +assignment instead of left side. For example: - will be changed to: - - ```python - some_var = 1 +```python +some_dict[ + "with_a_long_key" +] = some_looooooooong_module.some_looooooooooooooong_function_name( + first_argument, second_argument, third_argument +) +``` +will be changed to: - # Leading sticky comment - def my_func(): - ... - ``` +```python +some_dict["with_a_long_key"] = ( + some_looooooooong_module.some_looooooooooooooong_function_name( + first_argument, second_argument, third_argument + ) +) +``` ### Improved parentheses management -_Black_ will format parentheses around return annotations similarly to other sets of -parentheses. For example: +For dict literals with long values, they are now wrapped in parentheses. Unnecessary +parentheses are now removed. For example: ```python -def foo() -> (int): - ... - -def foo() -> looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong: - ... +my_dict = { + "a key in my dict": a_very_long_variable + * and_a_very_long_function_call() + / 100000.0, + "another key": (short_value), +} ``` will be changed to: ```python -def foo() -> int: - ... +my_dict = { + "a key in my dict": ( + a_very_long_variable * and_a_very_long_function_call() / 100000.0 + ), + "another key": short_value, +} +``` +### Improved multiline string handling -def foo() -> ( - looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong -): - ... -``` +_Black_ is smarter when formatting multiline strings, especially in function arguments, +to avoid introducing extra line breaks. Previously, it would always consider multiline +strings as not fitting on a single line. With this new feature, _Black_ looks at the +context around the multiline string to decide if it should be inlined or split to a +separate line. For example, when a multiline string is passed to a function, _Black_ +will only split the multiline string if a line is too long or if multiple arguments are +being passed. -And, extra parentheses in `await` expressions and `with` statements are removed. For -example: +For example, _Black_ will reformat ```python -with ((open("bla.txt")) as f, open("x")): - ... +textwrap.dedent( + """\ + This is a + multiline string +""" +) +``` + +to: -async def main(): - await (asyncio.sleep(1)) +```python +textwrap.dedent("""\ + This is a + multiline string +""") ``` -will be changed to: +And: ```python -with open("bla.txt") as f, open("x"): - ... +MULTILINE = """ +foobar +""".replace( + "\n", "" +) +``` +to: -async def main(): - await asyncio.sleep(1) +```python +MULTILINE = """ +foobar +""".replace("\n", "") ```