darglint 0.0.5

A utility for ensuring Google-style docstrings stay up to date with the source code.

A limited docstring linter which checks that function/method parameters are defined in their docstrings. Darglint expects docstrings to be formatted using the Google Python Style Guide.

Darglint is in a very early stage, and fails for a lot of things. Certain features, such as a robust command-line interface, still do not exist.

Installation

To install darglint, use pip.

pip install darglint

Or, clone the repository, cd to the directory, and

pip install .

Usage

Command Line use

Given a python source file, serializers.py, you would check the docstrings as follows:

darglint serializers.py

You can give an optional verbosity setting to darglint. For example,

darglint -v 3 *.py

Would give the most verbose warnings for each python module in the current directory.

Ignoring Errors in a Docstring

You can ignore specific errors in a particular docstring. The syntax is much like that of pycodestyle, etc. It generally takes the from of:

# noqa: <error> <argument>

Where <error> is the particular error to ignore (I402, or I201 for example), and <argument> is what (if anything) the ignore statement refers to (if nothing, then it is not specified).

Let us say that we want to ignore a missing return statement in the following docstring:

def we_dont_want_a_returns_section():
  """Returns the value, 3.

  # noqa: I201

  """
  return 3

We put the noqa anywhere in the top level of the docstring. However, this won’t work if we are missing something more specific, like a parameter. We may not want to ignore all missing parameters, either, just one particular one. For example, we may be writing a function that takes a class instance as self. (Say, in a bound celery task.) Then we would do something like:

def a_bound_function(self, arg1):
  """Do something interesting.

  Args:
    arg1: The first argument.

  # noqa: I101 arg1

  """
  arg1.execute(self)

So, the argument comes to the right of the error.

We may also want to mark excess documentation as being okay. For example, we may not want to explicitly catch and raise a ZeroDivisionError. We could do the following:

def always_raises_exception(x):
    """Raise a zero division error or type error.o

    Args:
      x: The argument which could be a number or could not be.

    Raises:
      ZeroDivisionError: If x is a number.  # noqa: I402
      TypeError: If x is not a number.  # noqa: I402

    """
    x / 0

So, in this case, the argument for noqa is really all the way to the left. (Or whatever description we are parsing.) We could also have put it on its own line, as # noqa: I402 ZeroDivisionError.

Features planned and implemented

The below list is all that defines the current roadmap for darglint. It is roughly sorted in order of importance.

• [x] Function definitions can be checked.

• [x] Methods definitions of top-level class can be checked.

• [x] Line number printout for function/method definition.

• [x] Add parsing of “Returns” section, and warn if differing from function definition.

• [x] Add command line interface.

• [x] Add multiple options for output.

• [x] Add checks for “Raises” section, like “Args”. Any exceptions raised in the body should be documented.

• [x] Add checks for “Yields” section, like “Returns”.

• [x] Add numbers to errors, ability to silence certain errors. (Use same formatting as pycodestyle.)

• [ ] Add TOML configuration file (use same interface as pydoclint, etc.)

• [ ] Add type hint integration. If an argument has a type hint, then the description of the argument, if it has a type, should match that.

• [ ] Add support for python versions earlier than 3.6.

• [ ] Syntastic support. (Syntastic is not accepting new checkers until their next API stabilizes, so this may take some time.)

• [ ] Check super classes of errors/exceptions raised to allow for more general descriptions in the interface.

Development

Install darglint. First, clone the repository:

git clone https://github.com/terrencepreilly/darglint.git

cd into the directory, create a virtual environment (optional), then setup:

cd darglint/
virtualenv -p python3.6 .env
source .env/bin/activate
pip install -e .

You can run the tests using

python setup.py test

Or, install pytest manually, cd to the project’s root directory, and run

pytest

Contributions welcome.