gistfile1.rb

module ActiveRecord::Associations::ClassMethods
    %w{has_and_belongs_to_many has_many has_one}.each do |meth|
      eval(<<METHOD_OVERRIDE
    # intercepting the #{meth} method to add the :as_component option
    def #{meth}_with_component(name, options = {})
      if options.delete(:as_component)
        options[:after_add] = :tell_my_parents
        self.components ||= []
        self.components << name
      end
      #{meth}_without_component(name, options)
    end
    alias_method_chain(:#{meth}, :component)
METHOD_OVERRIDE
    )
    end
end