Python Union 可以递归包含自己吗？

Question

是否可以创建一个类型，该类型是其中一项引用该类型的联合？

请参阅以下示例用例。这失败了，因为 Serialized 尚未声明。

from typing import List, Dict, Union 

class MyClass:
    # (...)

    Serialized = Union[Dict[str, Serialized], List[Serialized], str, int, float, bool]

    def serialize(self) -> Serialized:
        ...

Answer 1

根据PEP 484 which defines the type hints, you can use what they call forward references到尚未定义的引用类型。

所以你可以这样做：

from typing import Union, Dict, List

class MyClass:
    # (...)

    Serialized = Union[Dict[str, 'Serialized'], List['Serialized'], str, int, float, bool]

    def serialize(self) -> Serialized:
        ...

Python Union 可以递归包含自己吗？

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