Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.python > #40647

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

Show all headers | View raw

On Wednesday, 6 March 2013 16:22:56 UTC, Chris Angelico  wrote:
> 
> Effectively, you would need to have a
> subclass of list/dict/tuple/whatever that can respond to the change. 

This is certainly something I'd be interested in having, but I guess that would be fragile since the user would have the burden of having to remember to use those types.

> 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?
> 

I need to be able to perform complex operations on the object that may modify several properties, and then gather the properties at the end as an efficient way to see what has changed and to store those changes. Any comparison of before-and-after snapshots could work in theory, but in practice it could be expensive to produce the snapshots on larger objects and probably expensive to calculate the differences that way too. Performance is important so I would probably just go for an explicit function call to mark an attribute as having been modified rather than trying to do a diff like that. (It wouldn't work for rollbacks, but I can accept that.)

-- 
Ben Sizer

Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

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

csiph-web