591e9bbccb
Summary -- This PR implements the black preview style from https://github.com/psf/black/pull/4720. As of Python 3.14, you're allowed to omit the parentheses around groups of exceptions, as long as there's no `as` binding: **3.13** ```pycon Python 3.13.4 (main, Jun 4 2025, 17:37:06) [Clang 20.1.4 ] on linux Type "help", "copyright", "credits" or "license" for more information. >>> try: ... ... except (Exception, BaseException): ... ... Ellipsis >>> try: ... ... except Exception, BaseException: ... ... File "<python-input-1>", line 2 except Exception, BaseException: ... ^^^^^^^^^^^^^^^^^^^^^^^^ SyntaxError: multiple exception types must be parenthesized ``` **3.14** ```pycon Python 3.14.0rc2 (main, Sep 2 2025, 14:20:56) [Clang 20.1.4 ] on linux Type "help", "copyright", "credits" or "license" for more information. >>> try: ... ... except Exception, BaseException: ... ... Ellipsis >>> try: ... ... except (Exception, BaseException): ... ... Ellipsis >>> try: ... ... except Exception, BaseException as e: ... ... File "<python-input-2>", line 2 except Exception, BaseException as e: ... ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ SyntaxError: multiple exception types must be parenthesized when using 'as' ``` I think this ended up being pretty straightforward, at least once Micha showed me where to start :) Test Plan -- New tests At first I thought we were deviating from black in how we handle comments within the exception type tuple, but I think this applies to how we format all tuples, not specifically with the new preview style.
Ruff Formatter
The Ruff formatter is an extremely fast Python code formatter that ships as part of the ruff
CLI.
Goals
The formatter is designed to be a drop-in replacement for Black, but with an excessive focus on performance and direct integration with Ruff.
Specifically, the formatter is intended to emit near-identical output when run over Black-formatted code. When run over extensive Black-formatted projects like Django and Zulip, > 99.9% of lines are formatted identically. When migrating an existing project from Black to Ruff, you should expect to see a few differences on the margins, but the vast majority of your code should be unchanged.
If you identify deviations in your project, spot-check them against the intentional deviations enumerated below, as well as the unintentional deviations filed in the issue tracker. If you've identified a new deviation, please file an issue.
When run over non-Black-formatted code, the formatter makes some different decisions than Black, and so more deviations should be expected, especially around the treatment of end-of-line comments. For details, see Style Guide.
Getting started
Head to The Ruff Formatter for usage instructions and a comparison to Black.