import gc
from typing import TypeVar, Any, Optional, Callable, Iterable, Type, Sequence
T = TypeVar("T")
M = TypeVar("M")
[docs]def flatten(
obj: Any, flatten_dicts_by_values: bool = True, coerce: Optional[Callable[[T], M]] = None
) -> Iterable[M]:
"""Flatten an arbitrarily complex object.
:param obj: an obj to flatten.
:param flatten_dicts_by_values: if True, mapping will be flattened by values, otherwise by keys.
:param coerce: a callable used to coerce items of the resulting iterable to
:return: a recursively-constructed iterable of the object's constituents.
"""
if isinstance(obj, dict):
if flatten_dicts_by_values:
items = obj.values()
else:
items = obj.keys()
items = list(items)
yield from flatten(items, flatten_dicts_by_values=flatten_dicts_by_values, coerce=coerce)
elif isinstance(obj, list):
for item in obj:
yield from flatten(item, flatten_dicts_by_values=flatten_dicts_by_values, coerce=coerce)
else:
if coerce is not None:
yield coerce(obj)
else:
yield obj
[docs]def get_all_instances(cls: Type[T]) -> Sequence[T]:
"""Get all class instances.
:type cls: class whose instances need to be looked up.
"""
all_instances = []
all_objects = gc.get_objects()
for obj in all_objects:
if isinstance(obj, cls):
all_instances.append(obj)
return all_instances