pyflakes precommit hook, checks the index directly, needs importable pyflakes

pre-commit

#!/usr/bin/env python

import sys
import re
from subprocess import check_output, PIPE

import pyflakes.api


def git_file_content(fname):
    """Return file content as on git index."""
    return check_output(['git', 'show', ':'+fname])


def get_modified_files(ext):
    modified = re.compile(r'^(?:M|A).\s*(?P<name>.*\.%s)' % ext)
    output = check_output(['git', 'status', '--porcelain']).decode('utf-8')
    return [match.group('name')
            for line in output.splitlines()
            for match in [modified.match(line.strip())]
            if match]


def check_python():
    """Check modified python files in the index.
    Return number of warnings."""
    return sum([pyflakes.api.check(git_file_content(fname), fname)
                for fname in get_modified_files('py')])


def main():
    sys.exit(check_python())


if __name__ == '__main__':
    main()