At long last, _Black_ is no longer a beta product! This is the first non-beta release
and the first release covered by our new
[stability policy](https://black.readthedocs.io/en/stable/the_black_code_style/index.html#stability-policy).
Highlights
- **Remove Python 2 support** (2740)
- Introduce the `--preview` flag (2752)
Style
- Deprecate `--experimental-string-processing` and move the functionality under
`--preview` (2789)
- For stubs, one blank line between class attributes and methods is now kept if there's
at least one pre-existing blank line (2736)
- Black now normalizes string prefix order (2297)
- Remove spaces around power operators if both operands are simple (2726)
- Work around bug that causes unstable formatting in some cases in the presence of the
magic trailing comma (2807)
- Use parentheses for attribute access on decimal float and int literals (2799)
- Don't add whitespace for attribute access on hexadecimal, binary, octal, and complex
literals (2799)
- Treat blank lines in stubs the same inside top-level `if` statements (2820)
- Fix unstable formatting with semicolons and arithmetic expressions (2817)
- Fix unstable formatting around magic trailing comma (2572)
Parser
- Fix mapping cases that contain as-expressions, like `case {"key": 1 | 2 as password}`
(2686)
- Fix cases that contain multiple top-level as-expressions, like `case 1 as a, 2 as b`
(2716)
- Fix call patterns that contain as-expressions with keyword arguments, like
`case Foo(bar=baz as quux)` (2749)
- Tuple unpacking on `return` and `yield` constructs now implies 3.8+ (2700)
- Unparenthesized tuples on annotated assignments (e.g
`values: Tuple[int, ...] = 1, 2, 3`) now implies 3.8+ (2708)
- Fix handling of standalone `match()` or `case()` when there is a trailing newline or a
comment inside of the parentheses. (2760)
- `from __future__ import annotations` statement now implies Python 3.7+ (2690)
Performance
- Speed-up the new backtracking parser about 4X in general (enabled when
`--target-version` is set to 3.10 and higher). (2728)
- _Black_ is now compiled with [mypyc](https://github.com/mypyc/mypyc) for an overall 2x
speed-up. 64-bit Windows, MacOS, and Linux (not including musl) are supported. (1009,
2431)
Configuration
- Do not accept bare carriage return line endings in pyproject.toml (2408)
- Add configuration option (`python-cell-magics`) to format cells with custom magics in
Jupyter Notebooks (2744)
- Allow setting custom cache directory on all platforms with environment variable
`BLACK_CACHE_DIR` (2739).
- Enable Python 3.10+ by default, without any extra need to specify
`--target-version=py310`. (2758)
- Make passing `SRC` or `--code` mandatory and mutually exclusive (2804)
Output
- Improve error message for invalid regular expression (2678)
- Improve error message when parsing fails during AST safety check by embedding the
underlying SyntaxError (2693)
- No longer color diff headers white as it's unreadable in light themed terminals
(2691)
- Text coloring added in the final statistics (2712)
- Verbose mode also now describes how a project root was discovered and which paths will
be formatted. (2526)
Packaging
- All upper version bounds on dependencies have been removed (2718)
- `typing-extensions` is no longer a required dependency in Python 3.10+ (2772)
- Set `click` lower bound to `8.0.0` (2791)
Integrations
- Update GitHub action to support containerized runs (2748)
Documentation
- Change protocol in pip installation instructions to `https://` (#2761)
- Change HTML theme to Furo primarily for its responsive design and mobile support
(2793)
- Deprecate the `black-primer` tool (2809)
- Document Python support policy (2819)