Python中的动态继承

Question

假设我有两个不同的类实现

class ParentA:
    def initialize(self):
        pass

    def some_event(self):
        pass

    def order(self, value):
        # handle order in some way for Parent A


class ParentB:
    def initialize(self):
        pass

    def some_event(self):
        pass

    def order(self, value):
        # handle order in another for Parent B

我怎样才能动态地让一些第三类继承ParentA或ParentB基于这样的东西？

class MyCode:
    def initialize(self):
        self.initial_value = 1

    def some_event(self):
        # handle event
        order(self.initial_value)


# let MyCode inherit from ParentA and run
run(my_code, ParentA)

Answer 1

只需将类对象存储在变量中(在下面的示例中,它被命名base),并使用class语句的base-class-spec中的变量.

def get_my_code(base):

    class MyCode(base):
        def initialize(self):
          ...

    return MyCode

my_code = get_my_code(ParentA)

Answer 2

另外，您可以使用type内置的。可以调用的它带有参数：（name, bases, dct以最简单的形式）。

def initialize(self):
    self.initial_value = 1

def some_event(self):
    # handle event
    order(self.initial_value)

subclass_body_dict = {
    "initialize": initialize,
    "some_event": some_event
}

base_class = ParentA # or ParentB, as you wish

MyCode = type("MyCode", (base_class, ), subclass_body_dict)

这比snx2解决方案更明确，但仍然-我更喜欢他的方式。

PS。当然，您不必存储base_class或subclass_body_dict，也可以在type()调用中构建这些值，例如：

MyCode = type("MyCode", (ParentA, ), {
        "initialize": initialize,
        "some_event": some_event
    })