From: Pit Capitain <pit.capitain@...>
Date: 2007-07-23T04:20:13+09:00
Subject: Re: Overriding delegated methods

2007/7/22, Jesse Merriman <jesse.d.merriman@gmail.com>:
> (...) The solution that came to my mind
> was to create a delegating class that counts how many times #puts has been
> called, and restarts the process by killing the old wrapper object and creating
> a new one (...)

Thanks for the explanation. In this case you could try something like this:

  require 'delegate'

  class A
    def foo
      bar
    end

    def bar
       'original'
    end
  end

  class B < SimpleDelegator
    def initialize
      restart_delegate
    end

    def restart_delegate
      delegate = A.new
      __setobj__ delegate
      controller = self
      counter = 0
      class << delegate; self; end.class_eval do
        define_method :bar do
          counter += 1
          controller.restart_delegate if counter > 2
           "overridden in #{self}, original was #{super}"
        end
      end
    end
  end

  b = B.new
  4.times do
    puts b.foo
    puts b.bar
  end

The output:

  overridden in #<A:0x2e0b42c>, original was original
  overridden in #<A:0x2e0b42c>, original was original
  overridden in #<A:0x2e0b42c>, original was original
  overridden in #<A:0x2e0ab94>, original was original
  overridden in #<A:0x2e0ab94>, original was original
  overridden in #<A:0x2e0ab94>, original was original
  overridden in #<A:0x2e0a900>, original was original
  overridden in #<A:0x2e0a900>, original was original

Note how the A instance changes every three calls. The counter
increases both for internal and external calls. You can call the
original method with "super".

HTH

Regards,
Pit