在 Python 中，如何在使用類裝飾器時正確輸入？

Question

這是我第一次嘗試制作 Python 裝飾器，我謙虛地承認在這樣做時從許多 StackOverflow 帖子中汲取了靈感。 當我清理__instancecheck__方法時，最后兩個斷言停止觸發，但現在 PyCharm 的內置__instancecheck__對最后一個斷言不滿意。

Expected type 'Union[type, Tuple[Union[type, Tuple[Any, ...]], ...]]', got 'Multiton' instead.

打字問題的根源是什么，如何解決？

此外，在進行評論者推薦的__init__更改后，另一個警告浮出水面。

Local variable 'instance' might be referenced before assignment.

class Multiton(object):
    """ When init parameters match, reuse an old initialized object instead of making a new one. """
    def __init__(self, cls):
        # self.__dict__.update({'instances': list(), 'cls': cls})
        self.instances = list()
        self.cls = cls

    def __call__(self, *args, **kwargs):
        # make a key with the parameters
        key = (args, kwargs)

        # search for a matching old instance
        found = False
        for instance in self.instances:
            if instance['key'] == key:
                found = True
                break

        # if not found then create a new instance
        if not found:

            instance = {'key': key, 'object': self.cls(*args, **kwargs)}
            self.instances.append(instance)

        return instance['object']

    def __instancecheck__(self, other):
        return isinstance(other, self.cls)


@Multiton
class YourClass:

    def __init__(self, number):
        self.number = number


yc_1 = YourClass(1)
yc_2 = YourClass(2)
yc_two = YourClass(2)

assert yc_1 != yc_2
assert yc_2 == yc_two

assert not isinstance(yc_1, Multiton)
assert isinstance(yc_1, YourClass)

Answer 1

錯誤警告是 PyCharm 錯誤，希望 JetBrains 的優秀人員能盡快修復。

https://youtrack.jetbrains.com/issue/PY-38590 https://youtrack.jetbrains.com/issue/PY-49966