Apply allow-untyped-defs

update-mypy-flags.py

"""
Change the "default" flags for files in a project, so new files will require full type annotations.

If a file has no flags, it adds "allow-untyped-defs".
If a file already has "disallow-untyped-defs", that flag is removed.

Together with this script, one should update the mypy.ini file of a project:

    [mypy.app.*]
    disallow_untyped_defs = true
"""

import os
from argparse import ArgumentParser
from pathlib import Path


def main() -> None:
    parser = ArgumentParser(description="Add/remove mypy flags to .py files")
    parser.add_argument('directory', help='Directory to search for Python files')
    ns = parser.parse_args()

    for dirpath, dirnames, filenames in os.walk(ns.directory):
        dirpath = Path(dirpath)
        for filename in filenames:
            p = dirpath / filename
            if not p.is_file() or p.suffix != '.py':
                continue
            lines = p.read_bytes().splitlines(keepends=True)
            if lines:
                first = lines[0]
                op = None
                if b"# mypy: disallow-untyped-defs" in first:
                    op = "removed"
                    del lines[0]
                elif b"# mypy: allow-untyped-defs" not in first:
                    eol = first[-1:]
                    op = "added"
                    lines.insert(0, b"# mypy: allow-untyped-defs" + eol)
                if op is not None:
                    p.write_bytes(b"".join(lines))
                    print(f"{op}: {p}")


if __name__ == '__main__':
    main()