I want to add typing to a Python function that takes in a type as an argument (actually, a subtype of a specific class), and return an instance of that type. Think a factory that takes in the specific type as an argument, eg:
T = TypeVar('T', bound=Animal)
def make_animal(animal_type: Type[T]) -> T: # <-- what should `Type[T]` be?
return animal_type()
(obviously this is a very simplistic example, but it demonstrates the case)
This feels like something that should be possible, but I couldn't find how to properly type-hint this.
Not sure what your question is, the code you posted is perfectly valid Python code. There istyping.Type
that does exactly what you want:
from typing import Type, TypeVar
class Animal: ...
class Snake(Animal): ...
T = TypeVar('T', bound=Animal)
def make_animal(animal_type: Type[T]) -> T:
return animal_type()
reveal_type(make_animal(Animal)) # Revealed type is 'main.Animal*'
reveal_type(make_animal(Snake)) # Revealed type is 'main.Snake*'
See mypy output on mypy-play .
How about something like this?
from __future__ import annotations
from typing import Type
class Animal:
...
def make_animal(animal_type: Type[Animal]) -> Animal:
return animal_type()
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.