在构造函数中处理继承的更好方法

Question

I have the following BaseClass

class A(object):
    __metaclass__ = abc.ABCMeta
    def __init__(self, val1, val2):
        self.v1 = val1
        self.v2 = val2

and then some extended class:

class B(A):
    def __init__(self, *args, **kwargs):
        super(self.__class, self).__init(*args[:len(args)-1], **kwargs
        self.v3 = args[len(args)]

basically i want to call it in a way such that:

x = B(1, 2, 34)

but this seems that i need to have a specific order, how do implement init the right way so that the base class can initialize its v1,v2 variables and the extended class B can initialize the v3 value (in this case with 34).

Answer 1

You should be explicit about the required arguments for the super class A.__init__ . If you provide < 2 args to B then you would get an error.

class B(A):
    def __init__(self, val1, val2, *args):
        super(self.__class, self).__init__(val1, val2)
        self.v3 = args  # or args.pop() or whatever