Python:继承顺序？

Question

在下面的示例中，我有 2 个父类初始化/声明相同的变量。为什么要坐第一个类而不是第二堂课呢？这仅用于知识目的。

class ParentClass:
    one = 'I am the first variable'
    two = 'I am the second variable'
    three = 'I am the thirt variable'


class ParentClass2:
    three = 'I am the third variable'


class ChildClass(ParentClass, ParentClass2):
    two = 'Different Text'
    pass

childObject = ChildClass()
parentObject = ParentClass()

print(parentObject.one)
print(parentObject.two)
print(childObject.one)
print(childObject.two)
print(childObject.three)

输出:

I am the first variable

I am the second variable

I am the first variable

Different Text

I am the thirt variable

Answer 1

因为ParentClass在mro中排在第一位

 print(ChildClass.__mro__)
(<class '__main__.ChildClass'>, <class '__main__.ParentClass'>, <class '__main__.ParentClass2'>, <class 'object'>)

如果更改顺序，您将得到预期的输出:

class ChildClass(ParentClass2,ParentClass):

(<class '__main__.ChildClass'>, <class '__main__.ParentClass2'>, <class '__main__.ParentClass'>, <class 'object'>)

Python 从左到右检查属性，因此因为您首先有 ParentClass，所以您从 ParentClass 类获取属性