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!

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: v0.19.0
    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 (try prefixing with underscore?)
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);

as well as the following command-line arguments:

--max-line-length to control the maximum line length used by pycodestyle;
--no-pycodestyle if you don't want the pycodestyle checks;
--ban-relative-imports if you want to ban relative imports;
--ignore if you want to ignore some specific pycodestyle checks;
--files to pass a Regex pattern with which to match files to include;
--exclude to pass a Regex pattern with which to match files to exclude.

Configuration can be set project-wide in a .cython-lint.toml or pyproject.toml file at the root of the project. Here's an example:

[tool.cython-lint]
max-line-length = 88
ignore = ['E503', 'E504']
exclude = 'my_project/excluded_cython_file.pyx'

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
unnecessary list/set/dict + generator (just use a comprehension)