PEP 257 docstring style checker

pep257 is a static analysis tool for checking compliance with Python PEP 257.

The framework for checking docstring style is flexible, and custom checks can be easily added, for example to cover NumPy docstring conventions.

Installation

Use pip or easy_install:

pip install pep257

Alternatively, you can use pep257.py source file directly–it is self-contained.

pep257 is tested with Python 2.6, 2.7, 3.2, 3.3, 3.4, pypy and pypy3.

Example

$ pep257 --help
Usage: pep257 [options] [<file|dir>...]

Options:
--version             show program's version number and exit
-h, --help            show this help message and exit
-e, --explain         show explanation of each error
-s, --source          show source for each error
--ignore=<codes>      ignore a list comma-separated error codes, for
                        example: --ignore=D101,D202
--match=<pattern>     check only files that exactly match <pattern> regular
                        expression; default is --match='(?!test_).*\.py' which
                        matches files that don't start with 'test_' but end
                        with '.py'
--match-dir=<pattern>
                        search only dirs that exactly match <pattern> regular
                        expression; default is --match-dir='[^\.].*', which
                        matches all dirs that don't start with a dot
-d, --debug           print debug information
-v, --verbose         print status information
--count               print total number of errors to stdout

$ pep257 test.py
test.py:18 in private nested class `meta`:
        D101: Docstring missing
test.py:22 in public method `method`:
        D102: Docstring missing
...

$ pep257 test.py --explain
test.py:18 in private nested class `meta`:
        D101: Docstring missing

        All modules should normally have docstrings.  [...] all functions and
        classes exported by a module should also have docstrings. Public
        methods (including the __init__ constructor) should also have
        docstrings.

        Note: Public (exported) definitions are either those with names listed
              in __all__ variable (if present), or those that do not start
              with a single underscore.
...

$ pep257 test.py --source
test.py:15 in public class `class_`:
        D101: Docstring missing

    15: class class_:
    16:
...

$ pep257 test.py --count
test.py:18 in private nested class `meta`:
        D101: Docstring missing
test.py:22 in public method `method`:
        D102: Docstring missing
...
33

Error codes

All pep257 errors have unique codes. All codes start with a capital D and are grouped as follows:

Missing docstrings
D10{0,1,2,3} Public {module,class,method,function} missing.
Whitespace issues
D200 One-line docstrings should fit on one line with quotes.
D20{1,2} No blank lines allowed {before,after} docstring.
D20{3,4} 1 blank required {before,after} class docstring.
D205 Blank line required between one-line summary and description.
D206 Docstring should be indented with spaces, not tabs.
D20{7,8} Docstring {under,over}-indented.
D209 Put multi-line docstring closing quotes on separate line.
Quotes issues
D300 Use “”“triple double quotes”“”.
D301 Use r”“” if any backslashes in your docstring.
D302 Use u”“” for Unicode docstrings (Python 2 only).
Docstring content issues
D400 First line should end with a period.
D401 First line should be in imperative mood.
D402 First line should not be the function’s “signature”.

Configuration

pep257 looks for a config file in the root of the project (the common prefix of all checked files) and goes up in the directory tree until it finds one of the following files (in this order):

  • setup.cfg
  • tox.ini
  • .pep257

The first found file is read, and configurations in the [pep257] section are used, if such a section exists.

Config Example

[pep257]
verbose = true
ignore = D100,D203,D405
explain = true