thx for your quick (and complete) answers. to Alan G : I will try to see what setattr() and getattr() can do for me. I'm not used to this stuff.
to Alex Nedelcu : If I understand correctly : There are two different references (A.d in the dict of the class A and z.d in the dict of the object z) but on the same object, am I right ? (with z = A()) Alan G a écrit : >> class A(object): >> d = 50 >> def __init__(self): >> print "Hello" >> >> >>> z = A() >> >>> A.d >> 50 >> >>> z.d >> 50 >> 1) Why ?? d is not an object variable but a class variable !!! > > > Yes which means (definition of a class variable) that it's part of > every class and instance of the class. > >> object z, d is not defined (in my mind, not for Python, as you can >> see)(it's the same in Java : all static variables can be accessed >> from an object of the class or the class itself). > > > Thats what class attributes do, they are part of the class and > thus of instances of the class. After all, methods are defined at the > class level too and if they were not available to the instance > except by calling like: > > A.f(z) > > it would get very tiresome. > >> It's very dangerous because: >> >>> z.d += 1 >> >>> z.d >> 51 >> (now a object var is created called 'd') > > > And that I agree is confusing! THat is not standard class variable > behaviour and I personally don't like it. But there isn't any single > language I know where I like everything about it, so I live with it! > It's Guido's language, so he gets to choose how features work! :-) > >> Is it possible to have 'd' only for the class and not for instances >> of this class ? > > > I donl;t think so but it is possible that some of the new metaclass > stuff might allow that. Also you could probabnly use getattr()/settatr() > to do something similar. > > HTH, > > Alan G. > > _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
