See rotati blog post

enumerable_example.rb

class Coffee
  attr_accessor :name
  attr_accessor :strength

  def initialize(name, strength)
    @name = name
    @strength = strength
  end

  def <=>(other_coffee)
    self.strength <=> other_coffee.strength
  end

  def to_s
    "<name: #{name}, strength: #{strength}>"
  end
end

class CoffeeShop
  include Enumerable
  attr_accessor :coffees

  def initialize(*coffees)
    @coffees = coffees
  end

  def each
    @coffees.map{|coffee| yield coffee}
  end
end

laos = Coffee.new("Laos", 10)
angkor = Coffee.new("Angkor", 7)
nescafe = Coffee.new("Nescafe", 1)

my_favorite_coffee = [laos, angkor, nescafe]
puts "Sorting with array: #{my_favorite_coffee.sort}"
puts "Our arrays strongest Coffee sir! #{my_favorite_coffee.max}"

puts

cs = CoffeeShop.new(nescafe, laos, angkor)
puts "Sorting with CoffeeShop and Enumerable #{cs.sort}"
puts "Our shops strongest Coffee sir! #{cs.max}"