From: Tom Werner <tom@...>
Date: 2006-07-20T08:08:12+09:00
Subject: Object#extend inner workings

I've got a question regarding the inner workings of extend. Consider the 
following code that uses Object#extend twice:

class Klass
  def hello(options = {})
    p options
  end
end

module Mod1
  def hello(options = {})
    super(options.merge({:mod1 => true}))
  end
end

module Mod2
  def hello(options = {})
    super(options.merge({:mod2 => true}))
  end
end

k = Klass.new
k.hello           #=> {}

k.extend(Mod1)
k.hello           #=> {:mod1=>true}

k.extend(Mod2)
k.hello           #=> {:mod2=>true, :mod1=>true}

I was a bit surprised that the second extend didn't clobber the first. 
How is this handled by the Ruby interpreter? Is it creating more than 
one eigenclass?

Tom

-- 
Tom Werner
Helmets to Hardhats
Software Developer
tom@helmetstohardhats.org
www.helmetstohardhats.org