Ruby Enumerable example

colors_enum.rb

class ColorsEnum
  include Enumerable
  
  def initialize(colors)
    @colors = colors
  end

  def each(&block)
    block.call(@colors[0])
    @colors.shift
    ColorsEnum.new(@colors).each(&block) if @colors.any?
  end
end

enum = ColorsEnum.new(['red', 'orange', 'yellow', 'green'])
enum.each { |color| puts color }