如何对类型为泛型基类的任何子类的变量进行类型提示？

Question

我有两个链接的抽象基类，应该一起子类化。为了举一个最小的例子，我们假设它有一个类

TobeProcessed

，以及另一个类

Processor

，它对

TobeProcessed

类的实例执行一些处理。我用

Processor

类的类型作为类型参数创建了

Generic

TobeProcessed

。

from abc import ABC, abstractmethod
from typing import Generic, TypeVar


class TobeProcessed(ABC):
    pass


TobeProcessedType = TypeVar("TobeProcessedType", bound=TobeProcessed)


class Processor(ABC, Generic[TobeProcessedType]):
    @abstractmethod
    def process(self, to_be_processed: TobeProcessedType) -> None:
        pass

现在我有了这两个类的一些具体实现：

class TobeProcessedConcrete(TobeProcessed):
    pass


class ProcessorConcrete(Processor[TobeProcessedConcrete]):
    def process(self, to_be_processed: TobeProcessedConcrete) -> None:
        return None

最后，我有一个“包装”类，它有一个属性

processor

，它是

Processor

类的任何子类的实例。

class WrapperClass:
    processor: Processor

    def __init__(self, processor: Processor) -> None:
        self.processor = processor


processor = ProcessorConcrete()
wrapper = WrapperClass(processor=processor)

如果我用

mypy

和

--disallow-any-generics

（或

--strict

）检查这个，我会得到

WrapperClass

的两个错误，因为我省略了

Processor

的类型参数，这是有道理的。但是，如果我将

Processor

替换为

Processor[TobeProcessed]

，则会出现

wrapper = WrapperClass(processor=processor)

:

行错误

Argument "processor" to "WrapperClass" has incompatible type "ProcessorConcrete"; expected "Processor[TobeProcessed]"

.

有没有一种方法可以做到这一点而不会出现错误，并且不会使

mypy

不那么严格？

Answer 1

应该是

Processor[TobeProcessedType]

。

from abc import ABC, abstractmethod
from typing import Generic, TypeVar


class TobeProcessed(ABC):
    pass


TobeProcessedType = TypeVar("TobeProcessedType", bound=TobeProcessed)


class Processor(ABC, Generic[TobeProcessedType]):
    @abstractmethod
    def process(self, to_be_processed: TobeProcessedType) -> None:
        pass


class TobeProcessedConcrete(TobeProcessed):
    pass


class ProcessorConcrete(Processor[TobeProcessedConcrete]):
    def process(self, to_be_processed: TobeProcessedConcrete) -> None:
        return None


class WrapperClass(Generic[TobeProcessedType]):
    processor: Processor[TobeProcessedType]

    def __init__(self, processor: Processor[TobeProcessedType]) -> None:
        self.processor = processor


processor = ProcessorConcrete()
wrapper = WrapperClass(processor=processor)