Change Log¶

Unreleased¶

Black¶

Cell magics are now only processed if they are known Python cell magics. Earlier, all cell magics were tokenized, leading to possible indentation errors e.g. with %%writefile. (#2630)
Fix Python 3.10 support on platforms without ProcessPoolExecutor (#2631)
Reduce usage of the regex dependency (#2644)
Fix match statements with open sequence subjects, like match a, b: or match a, *b: (#2639) (#2659)
Fix match/case statements that contain match/case soft keywords multiple times, like match re.match() (#2661)
Fix assignment to environment variables in Jupyter Notebooks (#2642)
Add flake8-simplify and flake8-comprehensions plugins (#2653)
Fix parser error location on invalid syntax in a match statement (#2649)

21.11b1¶

Black¶

Bumped regex version minimum to 2021.4.4 to fix Pattern class usage (#2621)

21.11b0¶

Black¶

Warn about Python 2 deprecation in more cases by improving Python 2 only syntax detection (#2592)
Add experimental PyPy support (#2559)
Add partial support for the match statement. As it’s experimental, it’s only enabled when --target-version py310 is explicitly specified (#2586)
Add support for parenthesized with (#2586)
Declare support for Python 3.10 for running Black (#2562)

Integrations¶

Fixed vim plugin with Python 3.10 by removing deprecated distutils import (#2610)
The vim plugin now parses skip_magic_trailing_comma from pyproject.toml (#2613)

21.10b0¶

Black¶

Document stability policy, that will apply for non-beta releases (#2529)
Add new --workers parameter (#2514)
Fixed feature detection for positional-only arguments in lambdas (#2532)
Bumped typed-ast version minimum to 1.4.3 for 3.10 compatibility (#2519)
Fixed a Python 3.10 compatibility issue where the loop argument was still being passed even though it has been removed (#2580)
Deprecate Python 2 formatting support (#2523)

Blackd¶

Remove dependency on aiohttp-cors (#2500)
Bump required aiohttp version to 3.7.4 (#2509)

Black-Primer¶

Add primer support for –projects (#2555)
Print primer summary after individual failures (#2570)

Integrations¶

Allow to pass target_version in the vim plugin (#1319)
Install build tools in docker file and use multi-stage build to keep the image size down (#2582)

21.9b0¶

Packaging¶

Fix missing modules in self-contained binaries (#2466)
Fix missing toml extra used during installation (#2475)

21.8b0¶

Black¶

Add support for formatting Jupyter Notebook files (#2357)
Move from appdirs dependency to platformdirs (#2375)
Present a more user-friendly error if .gitignore is invalid (#2414)
The failsafe for accidentally added backslashes in f-string expressions has been hardened to handle more edge cases during quote normalization (#2437)
Avoid changing a function return type annotation’s type to a tuple by adding a trailing comma (#2384)
Parsing support has been added for unparenthesized walruses in set literals, set comprehensions, and indices (#2447).
Pin setuptools-scm build-time dependency version (#2457)
Exclude typing-extensions version 3.10.0.1 due to it being broken on Python 3.10 (#2460)

Blackd¶

Replace sys.exit(-1) with raise ImportError as it plays more nicely with tools that scan installed packages (#2440)

Integrations¶

The provided pre-commit hooks no longer specify language_version to avoid overriding default_language_version (#2430)

21.7b0¶

Black¶

Configuration files using TOML features higher than spec v0.5.0 are now supported (#2301)
Add primer support and test for code piped into black via STDIN (#2315)
Fix internal error when FORCE_OPTIONAL_PARENTHESES feature is enabled (#2332)
Accept empty stdin (#2346)
Provide a more useful error when parsing fails during AST safety checks (#2304)

Docker¶

Add new latest_release tag automation to follow latest black release on docker images (#2374)

Integrations¶

The vim plugin now searches upwards from the directory containing the current buffer instead of the current working directory for pyproject.toml. (#1871)
The vim plugin now reads the correct string normalization option in pyproject.toml (#1869)
The vim plugin no longer crashes Black when there’s boolean values in pyproject.toml (#1869)

21.6b0¶

Black¶

Fix failure caused by fmt: skip and indentation (#2281)
Account for += assignment when deciding whether to split string (#2312)
Correct max string length calculation when there are string operators (#2292)
Fixed option usage when using the --code flag (#2259)
Do not call uvloop.install() when Black is used as a library (#2303)
Added --required-version option to require a specific version to be running (#2300)
Fix incorrect custom breakpoint indices when string group contains fake f-strings (#2311)
Fix regression where R prefixes would be lowercased for docstrings (#2285)
Fix handling of named escapes (\N{...}) when --experimental-string-processing is used (#2319)

Integrations¶

The official Black action now supports choosing what version to use, and supports the major 3 OSes. (#1940)

21.5b2¶

Black¶

A space is no longer inserted into empty docstrings (#2249)
Fix handling of .gitignore files containing non-ASCII characters on Windows (#2229)
Respect .gitignore files in all levels, not only root/.gitignore file (apply .gitignore rules like git does) (#2225)
Restored compatibility with Click 8.0 on Python 3.6 when LANG=C used (#2227)
Add extra uvloop install + import support if in python env (#2258)
Fix –experimental-string-processing crash when matching parens are not found (#2283)
Make sure to split lines that start with a string operator (#2286)
Fix regular expression that black uses to identify f-expressions (#2287)

Blackd¶

Add a lower bound for the aiohttp-cors dependency. Only 0.4.0 or higher is supported. (#2231)

Packaging¶

Release self-contained x86_64 MacOS binaries as part of the GitHub release pipeline (#2198)
Always build binaries with the latest available Python (#2260)

Documentation¶

Add discussion of magic comments to FAQ page (#2272)
--experimental-string-processing will be enabled by default in the future (#2273)
Fix typos discovered by codespell (#2228)
Fix Vim plugin installation instructions. (#2235)
Add new Frequently Asked Questions page (#2247)
Fix encoding + symlink issues preventing proper build on Windows (#2262)

21.5b1¶

Black¶

Refactor src/black/__init__.py into many files (#2206)

Documentation¶

Replaced all remaining references to the master branch with the main branch. Some additional changes in the source code were also made. (#2210)
Sigificantly reorganized the documentation to make much more sense. Check them out by heading over to the stable docs on RTD. (#2174)

21.5b0¶

Black¶

Set --pyi mode if --stdin-filename ends in .pyi (#2169)
Stop detecting target version as Python 3.9+ with pre-PEP-614 decorators that are being called but with no arguments (#2182)

Black-Primer¶

Add --no-diff to black-primer to suppress formatting changes (#2187)

21.4b2¶

Black¶

Fix crash if the user configuration directory is inaccessible. (#2158)
Clarify circumstances in which Black may change the AST (#2159)
Allow .gitignore rules to be overridden by specifying exclude in pyproject.toml or on the command line. (#2170)

Packaging¶

Install primer.json (used by black-primer by default) with black. (#2154)

21.4b1¶

Black¶

Fix crash on docstrings ending with “\ “. (#2142)
Fix crash when atypical whitespace is cleaned out of dostrings (#2120)
Reflect the --skip-magic-trailing-comma and --experimental-string-processing flags in the name of the cache file. Without this fix, changes in these flags would not take effect if the cache had already been populated. (#2131)
Don’t remove necessary parentheses from assignment expression containing assert / return statements. (#2143)

Packaging¶

Bump pathspec to >= 0.8.1 to solve invalid .gitignore exclusion handling

21.4b0¶

Black¶

Fixed a rare but annoying formatting instability created by the combination of optional trailing commas inserted by Black and optional parentheses looking at pre-existing “magic” trailing commas. This fixes issue #1629 and all of its many many duplicates. (#2126)
Black now processes one-line docstrings by stripping leading and trailing spaces, and adding a padding space when needed to break up “”””. (#1740)
Black now cleans up leading non-breaking spaces in comments (#2092)
Black now respects --skip-string-normalization when normalizing multiline docstring quotes (#1637)
Black no longer removes all empty lines between non-function code and decorators when formatting typing stubs. Now Black enforces a single empty line. (#1646)
Black no longer adds an incorrect space after a parenthesized assignment expression in if/while statements (#1655)
Added --skip-magic-trailing-comma / -C to avoid using trailing commas as a reason to split lines (#1824)
fixed a crash when PWD=/ on POSIX (#1631)
fixed “I/O operation on closed file” when using –diff (#1664)
Prevent coloured diff output being interleaved with multiple files (#1673)
Added support for PEP 614 relaxed decorator syntax on python 3.9 (#1711)
Added parsing support for unparenthesized tuples and yield expressions in annotated assignments (#1835)
added --extend-exclude argument (PR #2005)
speed up caching by avoiding pathlib (#1950)
--diff correctly indicates when a file doesn’t end in a newline (#1662)
Added --stdin-filename argument to allow stdin to respect --force-exclude rules (#1780)
Lines ending with fmt: skip will now be not formatted (#1800)
PR #2053: Black no longer relies on typed-ast for Python 3.8 and higher
PR #2053: Python 2 support is now optional, install with python3 -m pip install black[python2] to maintain support.
Exclude venv directory by default (#1683)
Fixed “Black produced code that is not equivalent to the source” when formatting Python 2 docstrings (#2037)

Packaging¶

Self-contained native Black binaries are now provided for releases via GitHub Releases (#1743)

20.8b1¶

Packaging¶

explicitly depend on Click 7.1.2 or newer as Black no longer works with versions older than 7.0

20.8b0¶

Black¶

re-implemented support for explicit trailing commas: now it works consistently within any bracket pair, including nested structures (#1288 and duplicates)
Black now reindents docstrings when reindenting code around it (#1053)
Black now shows colored diffs (#1266)
Black is now packaged using ‘py3’ tagged wheels (#1388)
Black now supports Python 3.8 code, e.g. star expressions in return statements (#1121)
Black no longer normalizes capital R-string prefixes as those have a community-accepted meaning (#1244)
Black now uses exit code 2 when specified configuration file doesn’t exit (#1361)
Black now works on AWS Lambda (#1141)
added --force-exclude argument (#1032)
removed deprecated --py36 option (#1236)
fixed --diff output when EOF is encountered (#526)
fixed # fmt: off handling around decorators (#560)
fixed unstable formatting with some # type: ignore comments (#1113)
fixed invalid removal on organizing brackets followed by indexing (#1575)
introduced black-primer, a CI tool that allows us to run regression tests against existing open source users of Black (#1402)
introduced property-based fuzzing to our test suite based on Hypothesis and Hypothersmith (#1566)
implemented experimental and disabled by default long string rewrapping (#1132), hidden under a --experimental-string-processing flag while it’s being worked on; this is an undocumented and unsupported feature, you lose Internet points for depending on it (#1609)

Vim plugin¶

prefer virtualenv packages over global packages (#1383)

19.10b0¶

added support for PEP 572 assignment expressions (#711)
added support for PEP 570 positional-only arguments (#943)
added support for async generators (#593)
added support for pre-splitting collections by putting an explicit trailing comma inside (#826)
added black -c as a way to format code passed from the command line (#761)
–safe now works with Python 2 code (#840)
fixed grammar selection for Python 2-specific code (#765)
fixed feature detection for trailing commas in function definitions and call sites (#763)
# fmt: off/# fmt: on comment pairs placed multiple times within the same block of code now behave correctly (#1005)
Black no longer crashes on Windows machines with more than 61 cores (#838)
Black no longer crashes on standalone comments prepended with a backslash (#767)
Black no longer crashes on from … import blocks with comments (#829)
Black no longer crashes on Python 3.7 on some platform configurations (#494)
Black no longer fails on comments in from-imports (#671)
Black no longer fails when the file starts with a backslash (#922)
Black no longer merges regular comments with type comments (#1027)
Black no longer splits long lines that contain type comments (#997)
removed unnecessary parentheses around yield expressions (#834)
added parentheses around long tuples in unpacking assignments (#832)
added parentheses around complex powers when they are prefixed by a unary operator (#646)
fixed bug that led Black format some code with a line length target of 1 (#762)
Black no longer introduces quotes in f-string subexpressions on string boundaries (#863)
if Black puts parenthesis around a single expression, it moves comments to the wrapped expression instead of after the brackets (#872)
blackd now returns the version of Black in the response headers (#1013)
blackd can now output the diff of formats on source code when the X-Diff header is provided (#969)

19.3b0¶

new option --target-version to control which Python versions Black-formatted code should target (#618)
deprecated --py36 (use --target-version=py36 instead) (#724)
Black no longer normalizes numeric literals to include _ separators (#696)
long del statements are now split into multiple lines (#698)
type comments are no longer mangled in function signatures
improved performance of formatting deeply nested data structures (#509)
Black now properly formats multiple files in parallel on Windows (#632)
Black now creates cache files atomically which allows it to be used in parallel pipelines (like xargs -P8) (#673)
Black now correctly indents comments in files that were previously formatted with tabs (#262)
blackd now supports CORS (#622)

18.9b0¶

numeric literals are now formatted by Black (#452, #461, #464, #469):
- numeric literals are normalized to include _ separators on Python 3.6+ code
- added --skip-numeric-underscore-normalization to disable the above behavior and leave numeric underscores as they were in the input
- code with _ in numeric literals is recognized as Python 3.6+
- most letters in numeric literals are lowercased (e.g., in 1e10, 0x01)
- hexadecimal digits are always uppercased (e.g. 0xBADC0DE)
added blackd, see its documentation for more info (#349)
adjacent string literals are now correctly split into multiple lines (#463)
trailing comma is now added to single imports that don’t fit on a line (#250)
cache is now populated when --check is successful for a file which speeds up consecutive checks of properly formatted unmodified files (#448)
whitespace at the beginning of the file is now removed (#399)
fixed mangling pweave and Spyder IDE special comments (#532)
fixed unstable formatting when unpacking big tuples (#267)
fixed parsing of __future__ imports with renames (#389)
fixed scope of # fmt: off when directly preceding yield and other nodes (#385)
fixed formatting of lambda expressions with default arguments (#468)
fixed async for statements: Black no longer breaks them into separate lines (#372)
note: the Vim plugin stopped registering ,= as a default chord as it turned out to be a bad idea (#415)

18.6b4¶

hotfix: don’t freeze when multiple comments directly precede # fmt: off (#371)

18.6b3¶

typing stub files (.pyi) now have blank lines added after constants (#340)
# fmt: off and # fmt: on are now much more dependable:
- they now work also within bracket pairs (#329)
- they now correctly work across function/class boundaries (#335)
- they now work when an indentation block starts with empty lines or misaligned comments (#334)
made Click not fail on invalid environments; note that Click is right but the likelihood we’ll need to access non-ASCII file paths when dealing with Python source code is low (#277)
fixed improper formatting of f-strings with quotes inside interpolated expressions (#322)
fixed unnecessary slowdown when long list literals where found in a file
fixed unnecessary slowdown on AST nodes with very many siblings
fixed cannibalizing backslashes during string normalization
fixed a crash due to symbolic links pointing outside of the project directory (#338)

18.6b2¶

added --config (#65)
added -h equivalent to --help (#316)
fixed improper unmodified file caching when -S was used
fixed extra space in string unpacking (#305)
fixed formatting of empty triple quoted strings (#313)
fixed unnecessary slowdown in comment placement calculation on lines without comments

18.6b1¶

hotfix: don’t output human-facing information on stdout (#299)
hotfix: don’t output cake emoji on non-zero return code (#300)

18.6b0¶

added --include and --exclude (#270)
added --skip-string-normalization (#118)
added --verbose (#283)
the header output in --diff now actually conforms to the unified diff spec
fixed long trivial assignments being wrapped in unnecessary parentheses (#273)
fixed unnecessary parentheses when a line contained multiline strings (#232)
fixed stdin handling not working correctly if an old version of Click was used (#276)
Black now preserves line endings when formatting a file in place (#258)

18.5b1¶

added --pyi (#249)
added --py36 (#249)
Python grammar pickle caches are stored with the formatting caches, making Black work in environments where site-packages is not user-writable (#192)
Black now enforces a PEP 257 empty line after a class-level docstring (and/or fields) and the first method
fixed invalid code produced when standalone comments were present in a trailer that was omitted from line splitting on a large expression (#237)
fixed optional parentheses being removed within # fmt: off sections (#224)
fixed invalid code produced when stars in very long imports were incorrectly wrapped in optional parentheses (#234)
fixed unstable formatting when inline comments were moved around in a trailer that was omitted from line splitting on a large expression (#238)
fixed extra empty line between a class declaration and the first method if no class docstring or fields are present (#219)
fixed extra empty line between a function signature and an inner function or inner class (#196)

18.5b0¶

call chains are now formatted according to the fluent interfaces style (#67)
data structure literals (tuples, lists, dictionaries, and sets) are now also always exploded like imports when they don’t fit in a single line (#152)
slices are now formatted according to PEP 8 (#178)
parentheses are now also managed automatically on the right-hand side of assignments and return statements (#140)
math operators now use their respective priorities for delimiting multiline expressions (#148)
optional parentheses are now omitted on expressions that start or end with a bracket and only contain a single operator (#177)
empty parentheses in a class definition are now removed (#145, #180)
string prefixes are now standardized to lowercase and u is removed on Python 3.6+ only code and Python 2.7+ code with the unicode_literals future import (#188, #198, #199)
typing stub files (.pyi) are now formatted in a style that is consistent with PEP 484 (#207, #210)
progress when reformatting many files is now reported incrementally
fixed trailers (content with brackets) being unnecessarily exploded into their own lines after a dedented closing bracket (#119)
fixed an invalid trailing comma sometimes left in imports (#185)
fixed non-deterministic formatting when multiple pairs of removable parentheses were used (#183)
fixed multiline strings being unnecessarily wrapped in optional parentheses in long assignments (#215)
fixed not splitting long from-imports with only a single name
fixed Python 3.6+ file discovery by also looking at function calls with unpacking. This fixed non-deterministic formatting if trailing commas where used both in function signatures with stars and function calls with stars but the former would be reformatted to a single line.
fixed crash on dealing with optional parentheses (#193)
fixed “is”, “is not”, “in”, and “not in” not considered operators for splitting purposes
fixed crash when dead symlinks where encountered

18.4a4¶

don’t populate the cache on --check (#175)

18.4a3¶

added a “cache”; files already reformatted that haven’t changed on disk won’t be reformatted again (#109)
--check and --diff are no longer mutually exclusive (#149)
generalized star expression handling, including double stars; this fixes multiplication making expressions “unsafe” for trailing commas (#132)
Black no longer enforces putting empty lines behind control flow statements (#90)
Black now splits imports like “Mode 3 + trailing comma” of isort (#127)
fixed comment indentation when a standalone comment closes a block (#16, #32)
fixed standalone comments receiving extra empty lines if immediately preceding a class, def, or decorator (#56, #154)
fixed --diff not showing entire path (#130)
fixed parsing of complex expressions after star and double stars in function calls (#2)
fixed invalid splitting on comma in lambda arguments (#133)
fixed missing splits of ternary expressions (#141)

18.4a2¶

fixed parsing of unaligned standalone comments (#99, #112)
fixed placement of dictionary unpacking inside dictionary literals (#111)
Vim plugin now works on Windows, too
fixed unstable formatting when encountering unnecessarily escaped quotes in a string (#120)

18.4a1¶

added --quiet (#78)
added automatic parentheses management (#4)
added pre-commit integration (#103, #104)
fixed reporting on --check with multiple files (#101, #102)
fixed removing backslash escapes from raw strings (#100, #105)

18.4a0¶

added --diff (#87)
add line breaks before all delimiters, except in cases like commas, to better comply with PEP 8 (#73)
standardize string literals to use double quotes (almost) everywhere (#75)
fixed handling of standalone comments within nested bracketed expressions; Black will no longer produce super long lines or put all standalone comments at the end of the expression (#22)
fixed 18.3a4 regression: don’t crash and burn on empty lines with trailing whitespace (#80)
fixed 18.3a4 regression: # yapf: disable usage as trailing comment would cause Black to not emit the rest of the file (#95)
when CTRL+C is pressed while formatting many files, Black no longer freaks out with a flurry of asyncio-related exceptions
only allow up to two empty lines on module level and only single empty lines within functions (#74)

18.3a4¶

# fmt: off and # fmt: on are implemented (#5)
automatic detection of deprecated Python 2 forms of print statements and exec statements in the formatted file (#49)
use proper spaces for complex expressions in default values of typed function arguments (#60)
only return exit code 1 when –check is used (#50)
don’t remove single trailing commas from square bracket indexing (#59)
don’t omit whitespace if the previous factor leaf wasn’t a math operator (#55)
omit extra space in kwarg unpacking if it’s the first argument (#46)
omit extra space in Sphinx auto-attribute comments (#68)

18.3a3¶

don’t remove single empty lines outside of bracketed expressions (#19)
added ability to pipe formatting from stdin to stdin (#25)
restored ability to format code with legacy usage of async as a name (#20, #42)
even better handling of numpy-style array indexing (#33, again)

18.3a2¶

changed positioning of binary operators to occur at beginning of lines instead of at the end, following a recent change to PEP 8 (#21)
ignore empty bracket pairs while splitting. This avoids very weirdly looking formattings (#34, #35)
remove a trailing comma if there is a single argument to a call
if top level functions were separated by a comment, don’t put four empty lines after the upper function
fixed unstable formatting of newlines with imports
fixed unintentional folding of post scriptum standalone comments into last statement if it was a simple statement (#18, #28)
fixed missing space in numpy-style array indexing (#33)
fixed spurious space after star-based unary expressions (#31)

18.3a1¶

added --check
only put trailing commas in function signatures and calls if it’s safe to do so. If the file is Python 3.6+ it’s always safe, otherwise only safe if there are no *args or **kwargs used in the signature or call. (#8)
fixed invalid spacing of dots in relative imports (#6, #13)
fixed invalid splitting after comma on unpacked variables in for-loops (#23)
fixed spurious space in parenthesized set expressions (#7)
fixed spurious space after opening parentheses and in default arguments (#14, #17)
fixed spurious space after unary operators when the operand was a complex expression (#15)

18.3a0¶

first published version, Happy 🍰 Day 2018!
alpha quality
date-versioned (see: https://calver.org/)