Python 3 类型，具有任意数量包含类型的自定义可变参数泛型类型，如何? [英] Python 3 types, custom variadic generic type with arbitrary number of contained types, how?

问题描述

typing.Tuple 类可以与任意数量的类型参数一起使用，例如 Tuple[int, str, MyClass] 或 Tuple[str,浮动].我如何实现我自己的可以这样使用的类?我了解如何从 typing.Generic 继承.以下代码演示了这一点.

 from 打字 import TypeVar, GenericT = TypeVar("T")类事物(通用 [T]):def __init__(self, value: T):self.value = 价值def f(thing: Thing[int]):打印(东西.价值)如果 __name__ == '__main__':t = 东西(WTF")f(t)

上面的代码可以工作，但类型检查器(在我的例子中是 PyCharm)会发现 t 应该是 Thing[int] 类型而不是 东西[str].一切都很好，但是如何让 Thing 类支持任意数量的类型参数，就像 Tuple 那样?

解决方案

• 在您的示例中，t 的类型为 Thing，而不是 Thing[str].所以这个对象接受 T 的任何东西.
• 您可以像这样对其进行参数化:t2 = Thing[str]("WTF")
• 现在，对于您的问题，我认为您想使用 typing.Union 像这样:t3=Thing[Union[str,int,float]]("WTF")

顺便说一下，您可以使用 typing_inspect

<预><代码>>>>get_generic_type(t)__主要的事>>>get_generic_type(t2)__main__.Thing[str]>>>get_generic_type(t3)__main__.Thing[typing.Union[str, int, float]]

The class typing.Tuple can be used as with arbitrary number of type arguments, like Tuple[int, str, MyClass] or Tuple[str, float]. How do I implement my own class that can be used like that? I understand how to inherit from typing.Generic. The following code demonstrates this.

from typing import TypeVar, Generic


T = TypeVar("T")


class Thing(Generic[T]):
    def __init__(self, value: T):
        self.value = value


def f(thing: Thing[int]):
    print(thing.value)


if __name__ == '__main__':
    t = Thing("WTF")
    f(t)

The above code would work but the type checker (in my case PyCharm) would catch the fact that t should be of type Thing[int] and not Thing[str]. That's all fine, but how do I make the class Thing support arbitrary number of type arguments, like Tuple does?

解决方案

• In your example, t is of type Thing, not Thing[str]. So this object accepts anything for T.
• You can parametrize it like this : t2 = Thing[str]("WTF")
• now, for your question, I think you want to use typing.Union like this: t3=Thing[Union[str,int,float]]("WTF")

By the way, you can check the type of generics by using get_generic_type() from typing_inspect

>>> get_generic_type(t)
__main__.Thing
>>> get_generic_type(t2)
__main__.Thing[str]
>>> get_generic_type(t3)
__main__.Thing[typing.Union[str, int, float]]

这篇关于Python 3 类型，具有任意数量包含类型的自定义可变参数泛型类型，如何?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！