The Black Code Style#

Black is a PEP 8 compliant opinionated formatter with its own style.

While keeping the style unchanged throughout releases has always been a goal, the Black code style isn’t set in stone. It evolves to accommodate for new features in the Python language and, occasionally, in response to user feedback. Large-scale style preferences presented in The Black code style are very unlikely to change, but minor style aspects and details might change according to the stability policy presented below. Ongoing style considerations are tracked on GitHub with the design issue label.

Stability Policy#

The following policy applies for the Black code style, in non pre-release versions of Black:

  • The same code, formatted with the same options, will produce the same output for all releases in a given calendar year.

    This means projects can safely use black ~= 22.0 without worrying about major formatting changes disrupting their project in 2022. We may still fix bugs where Black crashes on some code, and make other improvements that do not affect formatting.

  • The first release in a new calendar year may contain formatting changes, although these will be minimised as much as possible. This is to allow for improved formatting enabled by newer Python language syntax as well as due to improvements in the formatting logic.

  • The --preview flag is exempt from this policy. There are no guarantees around the stability of the output with that flag passed into Black. This flag is intended for allowing experimentation with the proposed changes to the Black code style.

Documentation for both the current and future styles can be found: