gistfile1.rb

  attributes.each do |attr|
    attr.class.send(:alias_method, :original_set, :set)
    attr.class.send(:define_method, :set) do |instance, value|
      instance.send(:"#{name}_will_change!") unless value == self.get(instance)
      __send__(:original_set, instance, value)
    end
  end