Thanks, Did not know that.
Philippe Dennis Lee Bieber wrote: > On Thu, 27 Apr 2006 14:32:15 -0500, Philippe Martin > <[EMAIL PROTECTED]> declaimed the following in comp.lang.python: > >> >> What then is the point of the double underscore (if any) ?: > > To prevent masking/shadowing of inherited attributes... > >>>> class A(object): > ... def __init__(self): > ... self.__WhoMe = "From A" > ... print "A : ", dir(self) > ... super(A, self).__init__() > ... >>>> class B(object): > ... def __init__(self): > ... self.__WhoMe = 42 > ... print "B : ", dir(self) > ... super(B, self).__init__() > ... >>>> class Confusion(A, B): > ... def __init__(self): > ... self.__WhoMe = "I'm confuzzled" > ... print "Confusion: ", dir(self) > ... super(Confusion, self).__init__() > ... >>>> cab = Confusion() > Confusion: ['_Confusion__WhoMe', '__class__', '__delattr__', > '__dict__', '__doc__', '__getattribute__', '__hash__', '__init__', > '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', > '__setattr__', '__str__', '__weakref__'] > A : ['_A__WhoMe', '_Confusion__WhoMe', '__class__', '__delattr__', > '__dict__', '__doc__', '__getattribute__', '__hash__', '__init__', > '__module__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', > '__setattr__', '__str__', '__weakref__'] > B : ['_A__WhoMe', '_B__WhoMe', '_Confusion__WhoMe', '__class__', > '__delattr__', '__dict__', '__doc__', '__getattribute__', '__hash__', > '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__', > '__repr__', '__setattr__', '__str__', '__weakref__'] >>>> > > Note that A, B, and Confusion each have "__WhoMe". Also notice how > each __init__ invokes the parent module __init__; each one adds its > __WhoMe to the object without masking those defined in others. > > Without the __, you'd have only ONE attribute after all of that; as > shown next... > >>>> class A(object): > ... def __init__(self): > ... self._WhoMe = "From A" > ... print "A : ", dir(self) > ... super(A, self).__init__() > ... >>>> class B(object): > ... def __init__(self): > ... self._WhoMe = 42 > ... print "B : ", dir(self) > ... super(B, self).__init__() > ... >>>> class Confusion(A, B): > ... def __init__(self): > ... self._WhoMe = "I'm confuzzled" > ... print "Confusion: ", dir(self) > ... super(Confusion, self).__init__() > ... >>>> cab2 = Confusion() > Confusion: ['_WhoMe', '__class__', '__delattr__', '__dict__', > '__doc__', '__getattribute__', '__hash__', '__init__', '__module__', > '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', > '__str__', '__weakref__'] > A : ['_WhoMe', '__class__', '__delattr__', '__dict__', '__doc__', > '__getattribute__', '__hash__', '__init__', '__module__', '__new__', > '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', > '__weakref__'] > B : ['_WhoMe', '__class__', '__delattr__', '__dict__', '__doc__', > '__getattribute__', '__hash__', '__init__', '__module__', '__new__', > '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', > '__weakref__'] >>>> > -- > > ============================================================== < > > [EMAIL PROTECTED] | Wulfraed Dennis Lee Bieber KD6MOG < > > [EMAIL PROTECTED] | Bestiaria Support Staff < > > ============================================================== < > > Home Page: <http://www.dm.net/~wulfraed/> < > > Overflow Page: <http://wlfraed.home.netcom.com/> < -- http://mail.python.org/mailman/listinfo/python-list
