From: Harry Ohlsen <harryo@...>
Date: 2002-08-04T21:03:21+09:00
Subject: Detecting when an instance variable is created/set

Imagine we have a class like ...

   class Fred
      def initialize(a, b)
         @a = a
         @b = b
      end
   end

Can I write a method (of class Object or Kernel, perhaps) that will be called 
when the "@a = a" occurs?  What I'm looking for would be something like ...

   def instance_var_created(c, name, value)
      $stderr.puts "@#{name} of class #{c.class} set to #{value}"
   end

Is this possible?