[EMAIL PROTECTED] wrote: > Fredrik Lundh wrote: > >>reset your brain: >> >> http://effbot.org/zone/python-objects.htm > > > Neat link. > > Can you expand on this: > > >>a type (returned by type(x)) > > ... > >>You cannot change the type. > > > Especially what's going on here: > > >>>>class a(object): > > ... pass > ... > >>>>class b(a): > > ... pass > ... > >>>>x=b() >>>>x.attr=1 >>>>type(x) > > <class '__main__.b'> > >>>>type(y) > > <class '__main__.b'> > >>>>x.__class__=a >>>>type(x) > > <class '__main__.a'> > >>>>x.attr > > 1 > > It looks to me like x is still referencing the same object (and still > has the "attr" attribute) but its type has changed. Is that not right?
So what? That the flexibility of python allows for such a hack has nothing to do with x being totally unaware of the type of the object it points to. You only access values by names pointing/refering to them. If they are mutable, you can mutate them. If not (like strings, ints and floats), you have to rebind the name with a new value. But none of these changes what x is - and what not. Its a name, pointing to a value, and knows nothing about what it is actually bound to. Regards, Diez -- http://mail.python.org/mailman/listinfo/python-list
