Codestyle for coala

coala follows the PEP8 codestyle with a maximum line length of 80 characters including newline. Invoke coala to let it correct your code automatically.

Additional Style Guidelines

Documentation Comments

A documentation comment consists of 2 parts split by a newline:

  • the description of what it does
  • a list of the parameters it takes in and their descriptions, the return value it gives out and the exceptions it may raise

Nothing should be written on the first and last line where the docstring begins and ends, and each message in the documentation comment must end with a full-stop. Also, the description of all arguments, return value and errors raised shall be on a newline, indented by 4 spaces.


def area(length, breadth):
    Finds the area of a rectangle of the given length and breadth.

    :param length:
        The length of the rectangle.
    :param breadth:
        The breadth of the rectangle.
        The area of the rectangle.
    :raises ValueError:
        Raises ValueError if the arguments are not of type
        ``float`` or ``int``.

If the description for a param or other keywords exceeds 1 line, continue it in the next. Make sure that the second line is aligned below the first line.

Type Checking

If you want to assure that parameters have a certain type, you can use the enforce_signature decorator and simply annotate your function with the allowed types:

def concatenate_strings(a: str, b: str, c: (str, None)=None):
    if c is None:
        c = ""
    return a + b + c

This will raise a TypeError if a or b are not strings or c is not a string and not None.

Line Continuation

Since line continuation is not covered by PEP8 coding style guide you are supposed to keep your multiple-line lists, dicts, tuples, function definitions, function calls, and any such structures either:

  • stay on one line
  • span multiple lines that list one parameter/item each