Avoid specifying all arguments in a subclass

Question

I have a class:

class A(object):
    def __init__(self,a,b,c,d,e,f,g,...........,x,y,z)
        #do some init stuff

And I have a subclass w

Answer 1

In situations where some or all of the arguments passed to __init__ have default values, it can be useful to avoid repeating the __init__ method signature in subclasses.

In these cases, __init__ can pass any extra arguments to another method, which subclasses can override:

class A(object):
    def __init__(self, a=1, b=2, c=3, d=4, *args, **kwargs):
        self.a = a
        self.b = b
        # …
        self._init_extra(*args, **kwargs)

    def _init_extra(self):
        """
        Subclasses can override this method to support extra
        __init__ arguments.
        """

        pass


class B(A):
    def _init_extra(self, w):
        self.w = w