python bug?

James Henderson james at logicalprogression.net
Mon Jul 26 15:30:00 CEST 2004


Anthony Petropoulos wrote:
> Hi,
> 
> When running this simple code:
> -------
> class Dada:
>         a = []
>         def __init__(self, arg):
>                 self.a.append(arg)
> 
> d1 = Dada("pro")
> d2 = Dada("hoho")
> 
> print d1.a, d2.a
> ------------
> I get the output ['pro', 'hoho'] ['pro', 'hoho'], instead of what I
> expected: ['pro'] ['hoho'].
> 
> Is this a feature? Is there something I'm missing?
> 
> Anthony Petropoulos

Hi Anthony,

You've made "a" an attribute of the class, which means that it is shared 
by all instances.  To make it an instance attribute as you intended you 
should have written:

class Dada:
     def __init__(self, arg):
         self.a = [arg]

HTH,
James




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