On Thursday, August 30, 2012 4:30:59 PM UTC+2, Dave Angel wrote:
> On 08/30/2012 10:11 AM, Marco Nawijn wrote:
>
> > On Thursday, August 30, 2012 3:25:52 PM UTC+2, Hans Mulder wrote:
>
> >> <snip>
>
> >>
>
> > Learned my lesson today. Don't assume you know something. Test it first ;).
> > I have done quite some programming in Python, but did not know that class
> > attributes are still local to the instances.
>
>
>
> They're not. They're just visible to the instances, except where the
>
> instance has an instance attribute of the same name. Don't be confused
>
> by dir(), which shows both instance and class attributes.
>
>
>
> Please show me an example where you think you observe each instance
>
> getting a copy of the class attribute. There's probably some other
>
> explanation.
I don't have an example. It was just what I thought would happen. Consider the
following. In a class declaration like this:
class A(object):
attr_1 = 10
def __init__(self):
self.attr_2 = 20
If I instantiated it twice:
obj_1 = A()
obj_2 = A()
For both obj_1 and obj_2 attr_1 equals 10. What I thought would happen after
the following statement:
obj_1.attr_1 = 12
is that obj_2.attr_1 also equals 12. This is what surprised me a little, that's
all.
Marco
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