More assignment/copy novice confusion

[Arthur Siegel]

Laurent Pointal <laurent.pointal at l...>
>"Arthur Siegel" <ajs at i...> wrote in 
>news:mailman.1007306883.27068.python-list at p...:

>> Given a class:
>> 
>>>>> class  p:
>>              def __init__(self,a):
>>                  self.a=a

> But -
> 
>>>> m=p([1,2,3])
>>>> r=p([])

>Here r and m reference two **different** objects of class p, with their own 
>attributes.
>Try "r is m", and it will reply 0.

>>>> r.a=m.a

>Here m.a and r.a, which are attributes of different objects, reference the 
>same list.

>>>> m.a=[1,2,4]

>And now m.a reference another list.
So indeed if I do m.a[2]=4 instead ofm.a =[1,2,4] then>>>> m.a
> [1, 2, 4]
>>>> r.a
> [1, 2, 4]All of this is far from obvious, but of course doesin the end make perfect sense.Art


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