Black for code formatting

1. What is black

Black is a python code formatter that allows developers to focus on code itself. You can try it online at Black playground.

From their github:

Black is the uncompromising Python code formatter. By using it, you agree to cede control over minutiae of hand-formatting. In return, Black gives you speed, determinism, and freedom from pycodestyle nagging about formatting. You will save time and mental energy for more important matters.

The best way to explain it will using and example.

from seven_dwwarfs import Grumpy, Happy, Sleepy, Bashful, Sneezy, Dopey, Doc
x = {  'a':37,'b':42,

'c':927}

x = 123456789.1234

if very_long_variable_name is not None and \
 very_long_variable_name.field > 0 or \
 very_long_variable_name.is_debug:
 z = 'hello '+'world'
else:
 world = 'world'
 a = 'hello {}'.format(world)
 f = rf'hello {world}'
if (this
and that): y = 'hello ''world'#FIXME: https://github.com/ambv/black/issues/26
class Foo  (     object  ):
  def f    (self   ):
    return       37*-2
  def g(self, x,y=42):
      return y
def f  (   a: List[ int ]) :
  return      37-a[42-u :  y**3]
def very_important_function(template: str,*variables,file: os.PathLike,debug:bool=False,):
    """Applies `variables` to the `template` and writes to `file`."""
    with open(file, "w") as f:
     x = f.read()
regular_formatting = [
    0,  1,  2,
    3,  4,  5,
    6,  7,  8,
]

from seven_dwwarfs import (
    Grumpy,
    Happy,
    Sleepy,
    Bashful,
    Sneezy,
    Dopey,
    Doc,
)

x = {"a": 37, "b": 42, "c": 927}

x = 123_456_789.1234

if (
    very_long_variable_name is not None
    and very_long_variable_name.field > 0
    or very_long_variable_name.is_debug
):
    z = "hello " + "world"
else:
    world = "world"
    a = "hello {}".format(world)
    f = rf"hello {world}"
if this and that:
    y = (
        "hello " "world"
    )  # FIXME: https://github.com/ambv/black/issues/26


class Foo(object):
    def f(self):
        return 37 * -2

    def g(self, x, y=42):
        return y


def f(a: List[int]):
    return 37 - a[42 - u : y ** 3]


def very_important_function(
    template: str,
    *variables,
    file: os.PathLike,
    debug: bool = False,
):
    """Applies `variables` to the `template` and writes to `file`."""
    with open(file, "w") as f:
        x = f.read()


regular_formatting = [0, 1, 2, 3, 4, 5, 6, 7, 8]

2. Installation and usage of black

You can install black using pip with:

pip install black

You can ‘black’ any python file or directory with:

# Run on a file
black file.py

# Run on a folder
black src/

You can use a pyproject.toml file to configure some things in black. For example I like having a 100 line-length, so I would use:

pyproject.toml

[tool.black]
line-length = 100
py36 = true

3. Sublack

Sublack is a sublime extension to run black.

To install sublack you should:

1. Open sublime
2. Press CTRL + SHIFT + P
3. Write Package Controll: Install Package
4. Find sublack

After that you can use sublack by:

• CTRL + ALT + B: black the current file.
• CTRL + SHIFT + ALT + B: show a diff file of the changes that black is attempting to do.

But the best part will be if you set sublack to auto format the current file when saving. This way every time you save a file it will be blackened. To do so you should:

1. With sublime go to Preferences
2. Select Package Settings
3. Select sublack
4. Select Settings
5. Change black_on_save to true

I usually use sublime but there are black extensions for other programs as well.