使用Pyright的递归类型别名

Question

使用Pyright检查以下代码：

from typing import Union, TypeVar

T = TypeVar('T')
X_or_RecurListOf = Union[T, list['X_or_RecurListOf']]
x: X_or_RecurListOf[str] = ['asd']

生成以下错误：

  5:28 - error: Expression of type "list[str]" cannot be assigned to declared type "X_or_RecurListOf[str]"
    Type "list[str]" cannot be assigned to type "X_or_RecurListOf[str]"
      "list[str]" is incompatible with "str"
        TypeVar "_T@list" is invariant
          Type "str" cannot be assigned to type "X_or_RecurListOf[Type[T@X_or_RecurListOf]]"
            Type "str" cannot be assigned to type "T@X_or_RecurListOf"
            "str" is incompatible with "list[X_or_RecurListOf]" (reportGeneralTypeIssues)
1 error, 0 warnings, 0 infos 
Completed in 0.677sec

我做错了什么吗？

Answer 1

哦，我找到Pyright跌跌撞撞的地方了！

它希望在递归定义中包含类型参数：

X_or_RecurListOf = Union[T, list['X_or_RecurListOf[T]']] -注意[T]！

我不明白为什么这是必要的，但它对我来说是有效的，特别是因为我真正指的是X_or_RecurListOf[T]而不是X_or_RecurListOf[Any]。