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To: python-list@python.org
From: Terry Reedy <tjreedy@udel.edu>
Subject: Re: Need help with simple OOP Python question
Date: Mon, 05 Sep 2011 13:38:08 -0400
References: <dce02da0-c9c9-4331-aa2e-7d99f5e26cd1@g9g2000yqb.googlegroups.com> <87sjobo3es.fsf@benfinney.id.au> <93d65d9e-8a15-4423-94c0-3d385def24ed@et6g2000vbb.googlegroups.com>
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On 9/5/2011 9:15 AM, Kristofer Tengstr=C3=B6m wrote:
> Thanks everyone, moving the declaration to the class's __init__ method
> did the trick. Now there's just one little problem left. I'm trying to
> create a list that holds the parents for each instance in the
> hierarchy. This is what my code looks like now:
>
> -----------------------------------------
>
> class A:
>      def __init__(self, parents=3DNone):
>          self.sub =3D dict()
>          if parents:
>              self.parents =3D parents
>          else:
>              self.parents =3D []
>      def sub_add(self, cls):
>          hierarchy =3D self.parents
>          hierarchy.append(self)
>          obj =3D cls(hierarchy)
>          self.sub[obj.id] =3D obj

Indexing objects by their internal id is usually useless. Considier=20
whether you should be using sets rather than dicts.

--=20
Terry Jan Reedy