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Re: Creating an object that can track when its attributes are modified

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On Thu, Mar 7, 2013 at 3:07 AM, Ben Sizer <kylotan@gmail.com> wrote:
> I also believe that this won't catch modification to existing attributes as opposed to assignments: eg. if one of the attributes is a list and I append to it, this system won't notice. Is that something I can rectify easily?

The only way you could detect mutation of one of its attributes is
with that object's assistance. Effectively, you would need to have a
subclass of list/dict/tuple/whatever that can respond to the change.
Alternatively, you could retain a deep copy and do a comparison at
time of rollback; this, however, would have annoying consequences wrt
performance and other references and such.

What's the goal of this class? Can you achieve the same thing by
using, perhaps, a before-and-after snapshot of a JSON-encoded form of
the object?

ChrisA

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Creating an object that can track when its attributes are modified Ben Sizer <kylotan@gmail.com> - 2013-03-06 08:07 -0800
  Re: Creating an object that can track when its attributes are modified Chris Angelico <rosuav@gmail.com> - 2013-03-07 03:22 +1100
    Re: Creating an object that can track when its attributes are modified Ben Sizer <kylotan@gmail.com> - 2013-03-06 08:56 -0800
      Re: Creating an object that can track when its attributes are modified Chris Angelico <rosuav@gmail.com> - 2013-03-07 04:03 +1100
      Re: Creating an object that can track when its attributes are modified 88888 Dihedral <dihedral88888@googlemail.com> - 2013-03-06 13:07 -0800
      Re: Creating an object that can track when its attributes are modified 88888 Dihedral <dihedral88888@googlemail.com> - 2013-03-06 13:07 -0800
    Re: Creating an object that can track when its attributes are modified Ben Sizer <kylotan@gmail.com> - 2013-03-06 08:56 -0800
      Re: Creating an object that can track when its attributes are modified Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-07 00:07 +0000
        Re: Creating an object that can track when its attributes are modified Ben Sizer <kylotan@gmail.com> - 2013-03-06 16:26 -0800
          Re: Creating an object that can track when its attributes are modified Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-03-08 18:50 +0000
  Re: Creating an object that can track when its attributes are modified Lele Gaifax <lele@metapensiero.it> - 2013-03-06 17:56 +0100
  Re: Creating an object that can track when its attributes are modified Schneider <js@globe.de> - 2013-03-07 13:21 +0100

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