Playing with union of protocols

union_protocol.py

from abc import ABCMeta
from dataclasses import dataclass
from typing import (
    Any,
    ClassVar,
    Iterable,
    Protocol,
    Union,
    get_args,
    get_origin,
    runtime_checkable,
)

# PROTOCOLS

@runtime_checkable
class OtherIterable(Protocol):
    def __len__(self) -> int:
        """Returns the length of an object."""

    def __getitem__(self, item: Any):
        """Returns an item based on the received item."""


class UnionProtocol(ABCMeta):
    protocols: ClassVar[tuple[Any, ...]]

    def __instancecheck__(cls, instance):
        return any(
            isinstance(instance, protocol) for protocol in cls.protocols
        )


class ExtendedItarable(metaclass=UnionProtocol):
    protocols = (Iterable, OtherIterable)


# FUNCTIONS

def isinstanceprotocol(
    instance: Any,
    ref: Union[
        type,
        tuple[Union[type, tuple[Any, ...]], ...],
        Union[type, ...],
    ],
) -> bool:
    if get_origin(ref) == Union:
        return any(
            isinstance(instance, protocol) for protocol in get_args(ref)
        )
    return isinstance(instance, ref)


# CLASSES & TYPES

@dataclass
class Card:
    rank: str
    suit: str


class FrenchDeck:
    ranks: list[str] = [str(n) for n in range(2, 11)] + list('JQKA')
    suits: list[str] = 'spades diamonds clubs hearts'.split()

    _cards: list[Card]

    def __init__(self) -> None:
        self._cards = [
            Card(rank, suit)
            for suit in self.suits for rank in self.ranks
        ]

    def __len__(self) -> int:
        return len(self._cards)

    def __getitem__(self, position: int) -> Card:
        return self._cards[position]


ExtendedItarableUnion = Union[Iterable, OtherIterable]


if __name__ == '__main__':
    my_list = [1, 2, 3, 4]
    deck = FrenchDeck()

    # Using `UnionProtocol`
    if isinstance(my_list, ExtendedItarable):
        print('"my_list" is iterable')

    if isinstance(deck, ExtendedItarable):
        print('"deck" is iterable')

    # Using rewrited function
    if isinstanceprotocol(my_list, ExtendedItarableUnion):
        print('"my_list" is iterable')

    if isinstanceprotocol(deck, ExtendedItarableUnion):
        print('"deck" is iterable')