How to include a module

example-extends-vs-includes.rb

module Timeable
  def start_timer
    @timeable_timer = Time.now.utc
  end
  def end_timer
    Time.now.utc - @timeable_timer
  end
end

class DragRace
  include Timeable
end


race = DragRace.new

race.start_timer

sleep(3)

p race.end_timer

puts "See http://www.railstips.org/blog/archives/2009/05/15/include-vs-extend-in-ruby/ for more info"