FernyB

#!/usr/bin/env ruby

class Product
  def initialize(items)
    items.each {|item| Product.product(item) }
  end

  def self.product(item)
    code = %Q{
      def add_#{item}(item)
        @#{item} = [] unless @#{item}
        @#{item} << item
      end

      def display_#{item}s
        @#{item}.each {|item| puts item }
      end
    }
    class_eval(code)
  end
end

class Item < Product
  def initialize(*items)
    super(items)
  end
end

cart = Item.new(:book, :computer, :music)
cart.add_book(:Ruby) # => Add a book to our cart items

cart.display_books # => We want to display All books we have added
puts "\n"

cart.add_computer(:Apple)
cart.add_computer(:Dell)
cart.add_computer(:Sony)
cart.display_computers # => Display All Computers
puts "\n"

cart.add_music(’Modest Mouse‘)
cart.add_music(’Northstar‘)
cart.display_musics # => Display All Music Items