[Python] TypeError: Invalid annotation for 'value'. typing.Type[bool] is not a class

In Python 3.8 a new decorator for creating polymorphic functions was created, @singledispatch, which redirects Python to the correct implementation of your method depending on the type hints provided.

from datetime import datetime
from functools import singledispatch
from random import choice, randint
from typing import NoReturn, Type


@singledispatch
def load_value(value) -> NoReturn:
raise NotImplementedError(f'Unsupported type: {value}')


@load_value.register
def _(value: Type[bool]) -> bool:
return choice([False, True])


@load_value.register
def _(value: Type[int]) -> int:
return randint(0, 1000)


@load_value.register
def _(value: Type[datetime]) -> datetime:
return datetime.now()


print(load_value(bool))
print(load_value(int))
print(load_value(datetime))


However, I don't seem to be able to use types as arguments; please could you tell me what is wrong with my example? How should I annotate a parameter so that it is recognized as a type?

$ python ./register.py
Traceback (most recent call last):
File "./register.py", line 40, in <module>
def _(value: Type[bool]) -> bool:
File "/app/pyenv/versions/3.8.11/lib/python3.8/functools.py", line 860, in register
raise TypeError(
TypeError: Invalid annotation for 'value'. typing.Type[bool] is not a class.


The corresponding function must be called depending on the class passed as an argument.

Continue reading...