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
target-version = ['py37']
include = '\.pyi?$'
exclude = '''
(
/(
\.eggs # exclude a few common directories in the
| \.git # root of the project
| \.hg
| \.mypy_cache
| \.tox
| \.venv
| _build
| buck-out
| build
| dist
)/
| foo.py # also separately exclude a file named foo.py in
# the root of the project
)
'''
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.