darglint 0.0.8

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

A functional docstring linter which checks whether a docstring’s description matches the actual function/method implementation. Darglint expects docstrings to be formatted using the Google Python Style Guide.

Darglint is in a very early stage, and may fail for a lot of things. See the Features planned section for an idea of where the project is going.

Feel free to submit an issue/pull request if you spot a problem or would like a feature in darglint.

Installation

To install darglint, use pip.

pip install darglint

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

pip install .

Configuration

darglint can be configured using a configuration file. The configuration file must be named either .darglint, setup.cfg, or tox.ini. It must also have a section starting with the section header, [darglint]. Finally, the configuration file must be located either in the directory darglint is called from, or from a parent directory of that working directory.

Currently, the configuration file only allows us to ignore errors. For example, if we would like to ignore ExcessRaiseErrors (because we know that an underlying function will raise an exception), then we would add its error code to a file named .darglint:

[darglint]
ignore=I402

We can ignore multiple errors by using a comma-separated list:

[darglint]
ignore=I402,I103

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 2 *.py

Would give a description of the error along with information as to this specific instance. The default verbosity is 1, which gives the filename, function name, line number, error code, and some general hints.

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.

The below list is all that defines the current roadmap for darglint. It is roughly sorted in order of importance. To see the most recently implemented features, see the CHANGELOG.

• [ ] ALE support.

• [ ] Take an argument which supports a formatting string for the error message. That way, anyone can specify their own format.

• [ ] Optional checking for docstring style compliance.

• [ ] Robust logging for errors caused/encountered by darglint.

• [ ] 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 and Contributions

Development Setup

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

This project tries to conform by the styles imposed by pycodestyle and pydocstyle, as well as by darglint itself.

Contribution

If you would like to tackle an issue or feature, email me or comment on the issue to make sure it isn’t already being worked on. Contributions will be accepted through pull requests. New features should include unit tests, and, of course, properly formatted documentation.