super() 的多重继承问题

Question

我遇到了一个我似乎无法弄清楚的多重继承问题。这是一个非常抽象的最小示例，它重现了我的错误（我的代码比这复杂得多）。

class Thing(object):
    def __init__(self, x=None):
        self.x = x

class Mixin(object):
    def __init__(self):
        self.numbers = [1,2,3]

    def children(self):
        return [super().__init__(x=num) for num in self.numbers]

class CompositeThing(Mixin, Thing):
    def __init__(self):
        super().__init__()

    def test(self):
        for child in self.children():
            print(child.x)

obj = CompositeThing()
obj.test()

根据 this，我希望 children() 方法能够 return 从 self.numbers 构建的 Thing 列表。相反，我得到 TypeError: super(type, obj): obj must be an instance or subtype of type。顺便说一句，如果我不调用构造函数并允许 children 到 return super() 3 次（即未实例化的超类），也会发生同样的事情。任何想法为什么会发生这种情况？

提前致谢！

Answer 1

在代码的第 9 行中，您似乎正在尝试调用 object 的 __init__。我假设你打算让 Mixin 继承自 Thing.

class Thing(object):
    def __init__(self, x=None):
        self.x = x

class Mixin(Thing):
    def __init__(self):
        self.numbers = [1,2,3]

    def children(self):
        return [super().__init__(x=num) for num in self.numbers] # Now calls Thing.__init__ instead of object.__init__

class CompositeThing(Mixin, Thing):
    def __init__(self):
        super().__init__()

    def test(self):
        for child in self.children():
            print(child.x)

obj = CompositeThing()
obj.test()

Answer 2

其实，我想通了。有两个问题：(1) because comprehensions in Py3 have their own scope - this was causing the TypeError I was experiencing. (2) What I was really trying to do was create a new instance of the parent，而不是从父级调用方法。为了清楚起见，我已经针对后一个问题发布了一个新问题。

super() 的多重继承问题

Multiple inheritance problem with super()

python-3.x

multiple-inheritance

mixins

super