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[英]mypy error:Incompatible types in assignment (expression has type “List[str]”, variable has type “str”)
[英]mypy incompatible types list<nothing> has the type list<str>
我正在使用带有代码的提示工具包 python 库:
from __future__ import annotations
from prompt_toolkit.shortcuts import checkboxlist_dialog
results: list[str] = checkboxlist_dialog(
title="CheckboxList dialog",
text="What would you like in your breakfast ?",
values=[
("eggs", "Eggs"),
("bacon", "Bacon"),
("croissants", "20 Croissants"),
("daily", "The breakfast of the day"),
],
).run()
当我运行 mypy 0.931 时,我得到:
test.py:4: error: Incompatible types in assignment (expression has type "List[<nothing>]", variable has type "List[str]")
test.py:4: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
test.py:4: note: Consider using "Sequence" instead, which is covariant
test.py:7: error: Argument "values" to "checkboxlist_dialog" has incompatible type "List[Tuple[str, str]]"; expected "Optional[List[Tuple[<nothing>, Union[str, MagicFormattedText, List[Union[Tuple[str, str], Tuple[str, str, Callable[[MouseEvent], None]]]], Callable[[], Any], None]]]]"
我不确定问题是否出在我的代码上,因为返回值类似于['eggs', 'bacon']
,它是一个list[str]
。 mypy 的这个错误也很奇怪,因为我认为我不应该在这里使用协变。 关于可能是什么问题的任何提示?
我认为问题在于 mypy 关于checkboxlist_dialog
function 的信息很少,当然也不知道它的返回类型可以从value
参数中找出。
你可能不得不写:
from typing import cast
results = cast(list[string], checkboxlist_dialog(....))
它告诉 mypy 你知道你在做什么,并且返回类型实际上是一个list[string]
,不管它怎么想。
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