Python 3.6 type «enforcement» (/ check) through annotations or custom list of types

type_enforcement.py

#!/usr/bin/env python3
#  -*- coding: utf-8 -*-


import logging.config
import functools
from typing import Callable, Union

__author__ = 'Thomas Hesse'

L = logging.getLogger(__name__)
L.debug(f'Loaded module: {__name__}.')


def accepts(*types):
    """Decorate any callable to force type checking on arguments.

    :param types: *Optional.* When specified, these types are used over the python3 annotations.
    """

    def check_accepts(f: Callable, *_types) -> Callable:
        _types = _types or tuple(f.__annotations__.values())
        assert len(_types) == f.__code__.co_argcount

        @functools.wraps(f)
        def new_f(*args, **kwargs) -> Callable:
            for (a, t) in zip(args, _types):
                if not isinstance(a, t.__args__ if type(t) is type(Union) else t):
                    err_msg = f'Call to function {f.__name__}: Argument {a} with type {type(a)} does not match type {t}'
                    L.error(err_msg)
                    raise AttributeError(err_msg)
            return f(*args, **kwargs)

        return new_f

    return lambda f: check_accepts(f, *types)

Credits to the people from reddit.com/r/learnpython: Link to the thread that supported me in this