mypy：如何指定混合类型的列表（或序列）？

发布于 2025-01-29 12:47:53 字数 966 浏览 3 评论 0原文

这里有一些代码：

import typing

class A:
    def f(self):
        print("A")

class B:
    def f(self):
        print("B")

C = typing.Union[A,B]
Sequence_C = typing.Sequence[C]

a = A()
b = B()

d : Sequence_C = [a]+[b]

mypy提供了此错误：

error: List item 0 has incompatible type "B"; expected "A"

我的（可能是错误的）毫无疑问：

C = typing.Union[A,B]
Sequence_C = typing.Sequence[C]

表示sequence_c的实例是B的实例的序列。

我想创建一个类型的sequence_c A和B.

我的动机是我需要实施“ F”方法的实例列表。

请注意，更明确无济于事：（

import typing

class S:
    def f(self):
        raise NotImplementedError()

class A(S):
    def f(self):
        print("A")

class B(S):
    def f(self):
        print("B")

Sequence_S = typing.Sequence[S]

a = A()
b = B()

d : Sequence_S = [a]+[b]

相同的错误）

原文

Here some code:

import typing

class A:
    def f(self):
        print("A")

class B:
    def f(self):
        print("B")

C = typing.Union[A,B]
Sequence_C = typing.Sequence[C]

a = A()
b = B()

d : Sequence_C = [a]+[b]

mypy provides this error:

error: List item 0 has incompatible type "B"; expected "A"

My (possibly incorrect) undestanding:

C = typing.Union[A,B]
Sequence_C = typing.Sequence[C]

means that instances of Sequence_C are either sequences of instances of A or sequences of instances of B.

I would like to create a type Sequence_C which are sequences of instances of both A and B.

My motivation is that I need a list of instances implementing a "f" method.

Note that being more explicit did not help:

import typing

class S:
    def f(self):
        raise NotImplementedError()

class A(S):
    def f(self):
        print("A")

class B(S):
    def f(self):
        print("B")

Sequence_S = typing.Sequence[S]

a = A()
b = B()

d : Sequence_S = [a]+[b]

(same error)

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逆流 2025-02-05 12:47:53

您需要告诉类型检查器，[a]和[b]应解释为sequence_s，而不是键入。序列[a]（或[b]）明确，例如= strict＆amp; gist = 32daac7d4b33333333333bcde9fd5f86002ef4c0“ rel =“ nofollow noreferrer”>像这样：

import typing

class S:
    def f(self) -> None:
        raise NotImplementedError()

class A(S):
    def f(self) -> None:
        print("A")

class B(S):
    def f(self) -> None:
        print("B")

Sequence_S = typing.Sequence[S]

a: Sequence_S = [A()]
b: Sequence_S = [B()]

# Sequences don't support "+", see https://docs.python.org/3/glossary.html#term-sequence
d : Sequence_S = [*a, *b]

You need to tell the type checker that [a] and [b] are to be interpreted as Sequence_S, and not typing.Sequence[A] (or [B]) explicitly, e.g. like this:

import typing

class S:
    def f(self) -> None:
        raise NotImplementedError()

class A(S):
    def f(self) -> None:
        print("A")

class B(S):
    def f(self) -> None:
        print("B")

Sequence_S = typing.Sequence[S]

a: Sequence_S = [A()]
b: Sequence_S = [B()]

# Sequences don't support "+", see https://docs.python.org/3/glossary.html#term-sequence
d : Sequence_S = [*a, *b]

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