Find all subclasses of a given class

subclasses.py

"""Find all subclasses of a class with queue or stack."""

import collections
from collections.abc import Collection, Iterator


def itersubclasses(parent: type, /, *,
                   proper: bool = True,
                   exclude: Collection[type] = (type,)) -> Iterator[type]:
    """Yield `parent` subclasses recursively in breadth-first order."""
    queue = collections.deque(parent.__subclasses__() if proper else [parent])
    seen = set(exclude)
    while queue:
        if (cls := queue.popleft()) not in seen:
            seen.add(cls)
            yield cls
            queue.extend(cls.__subclasses__())


print(itersubclasses.__doc__)
for cls in itersubclasses(object):
    print(cls)


def itersubclasses(parent: type, /, *,
                   proper: bool = True,
                   exclude: Collection[type] = (type,)) -> Iterator[type]:
    """Yield `parent` subclasses recursively in depth-first order."""
    stack = parent.__subclasses__()[::-1] if proper else [parent]
    seen = set(exclude)
    while stack:
        if (cls := stack.pop()) not in seen:
            seen.add(cls)
            yield cls
            stack.extend(reversed(cls.__subclasses__()))


print('', itersubclasses.__doc__, sep='\n')
for cls in itersubclasses(object):
    print(cls)