From: dblack@...
Date: 2006-08-28T06:06:31+09:00
Subject: Re: Detecting when an object's instance variables are modified

Hi --

On Mon, 28 Aug 2006, David Vallner wrote:

> Paul Murton wrote:
>> I have a whole load of objects which I would like to periodically dump as 
>> YAML. However, in order to save on resources, I would prefer to only dump 
>> those whose instance variables have changed since the last dump.
>> 
>> Is it possible to somehow 'mark' an object when the value any of its 
>> instance variables is changed?
>> 
>
> For the more "magical" way, you could play around with set_trace_func to 
> monitor setters. Would probably be horribly, terribly slow.
>
> It's probably best to have your objects trace changes by design. Modify the 
> Object class to have a #dirty? and #clean! method, and alias / redefine the 
> #attr_writer method to generate methods that will set the dirty flag when 
> used?

I was thinking of something similar, but using Observable -- but the
problem is that it would only work for instance variable changes that
go through attr_writer.


David

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