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我怎么能够把一个没有界定的阶层划入一个 Python类变量?
原标题:How can I put an instance of a not-yet-defined class in a Python class variable?

我有两个班级,比如,我叫A级和B级。 d 希望在A类中产生班级和B级的情况,如下所示:

class ClassA:
    CLASSVAR=ClassA(ClassB())
    def __init__(self,arg):
        pass
class ClassB:
    def __init__(self):
        pass

然而,当我尝试这样做时,我有以下错误:NameError:名次 A没有定义

能否获得诸如<代码>CLASSVAR等类别变量,从而产生<代码>ClassA和ClassB的情况,而不必发现这一错误?

最佳回答

在设立课堂后,必须分配:

class ClassA:
    def __init__(self, arg):
        self.arg = arg
class ClassB:
    pass
ClassA.CLASSVAR = ClassA(ClassB())

If you want to appease mypy, you can provide an annotation for the class variable:

from typing import ClassVar

class ClassA:
    CLASSVAR: ClassVar[ ClassA ]
    def __init__(self, arg):
        self.arg = arg
class ClassB:
    pass
ClassA.CLASSVAR = ClassA(ClassB())
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