cython-lint 0.12.0

A linter for Cython files

cython-lint

Everything flake8 used to do (by accident), plus much more.

A tool and pre-commit hook to lint Cython files.

Used by

Here's some major projects using cython-lint - is yours missing? Feel free to open a pull request!

• open library
• pandas
• pylibssh
• pymatgen
• RAPIDS cuspatial
• RAPIDS cudf
• RAPIDS Memory Manager
• scipy
• yt

In addition:

• it found an actual bug in spaCy;
• it found a type issue in CuPy.

Installation

$ pip install cython-lint

Usage as a pre-commit hook

See pre-commit for instructions

Sample .pre-commit-config.yaml:

-   repo: https://github.com/MarcoGorelli/cython-lint
    rev: v0.12.0
    hooks:
    -   id: cython-lint
    -   id: double-quote-cython-strings

Command-line example

$ cython-lint my_file_1.pyx my_file_2.pyx
my_file_1.pyx:54:5: 'get_conversion_factor' imported but unused
my_file_2.pyx:1112:38: 'mod' defined but unused
my_file_3.pyx:4:9: dangerous default value!
my_file_3.pyx:5:9: comma after base type in definition

Configuration

The following configuration options are available:

• exclude lines by including a # no-cython-lint comment (analogous to # noqa in flake8);
• use the command-line argument --max-line-length to control the maximum line length used by pycodestyle;
• use the command-line argument --no-pycodestyle if you don't want the pycodestyle checks.

Which checks are implemented?

• assert statement with tuple condition (always true...)
• comma after base type definition (e.g. cdef ndarray, arr)
• comparison between constants
• dangerous default value
• dict key repeated
• dict key variable repeated
• f-string without placeholders
• if-statement with tuple condition (always true...)
• late-binding closures https://docs.python-guide.org/writing/gotchas/#late-binding-closures
• pointless string statement
• pycodestyle nitpicks (which you can turn off with --no-pycodestyle)
• repeated element in set
• .strip, .rstrip, or .lstrip used with repeated characters
• unnecessary list index lookup
• unnecessary import alias
• variable defined but unused
• variable imported but unused

In addition, the following automated fixers are implemented:

• double-quote-cython-strings (replace single quotes with double quotes, like the black formatter does)

More to come! Requests welcome!