pyproject.toml¶
Black is able to read project-specific default values for its
command line options from a pyproject.toml
file. This is
especially useful for specifying custom --include
and --exclude
patterns for your project.
Pro-tip: If you’re asking yourself “Do I need to configure anything?” the answer is “No”. Black is all about sensible defaults.
What on Earth is a pyproject.toml
file?¶
PEP 518 defines
pyproject.toml
as a configuration file to store build system
requirements for Python projects. With the help of tools
like Poetry or
Flit it can fully replace the
need for setup.py
and setup.cfg
files.
Where Black looks for the file¶
By default Black looks for pyproject.toml
starting from the common
base directory of all files and directories passed on the command line.
If it’s not there, it looks in parent directories. It stops looking
when it finds the file, or a .git
directory, or a .hg
directory,
or the root of the file system, whichever comes first.
If you’re formatting standard input, Black will look for configuration starting from the current working directory.
You can also explicitly specify the path to a particular file that you
want with --config
. In this situation Black will not look for any
other file.
If you’re running with --verbose
, you will see a blue message if
a file was found and used.
Please note blackd
will not use pyproject.toml
configuration.
Configuration format¶
As the file extension suggests, pyproject.toml
is a TOML file. It contains separate
sections for different tools. Black is using the [tool.black]
section. The option keys are the same as long names of options on
the command line.
Note that you have to use single-quoted strings in TOML for regular
expressions. It’s the equivalent of r-strings in Python. Multiline
strings are treated as verbose regular expressions by Black. Use [ ]
to denote a significant space character.
Example
pyproject.toml
[tool.black]
line-length = 88
py36 = true
include = '\.pyi?$'
exclude = '''
/(
\.git
| \.hg
| \.mypy_cache
| \.tox
| \.venv
| _build
| buck-out
| build
| dist
# The following are specific to Black, you probably don't want those.
| blib2to3
| tests/data
)/
'''
Lookup hierarchy¶
Command-line options have defaults that you can see in --help
.
A pyproject.toml
can override those defaults. Finally, options
provided by the user on the command line override both.
Black will only ever use one pyproject.toml
file during an entire
run. It doesn’t look for multiple files, and doesn’t compose
configuration from different levels of the file hierarchy.