require 'forwardable'
 
module SingletonCollection
  module Methods  
    extend Forwardable
    def_delegators :@storage, *Array.instance_methods(inherited=false)
    
    attr_accessor :current_index
    
    def current
      self[current_index]
    end    
  end
  
  def self.extended(singleton)
    singleton.extend Methods
    singleton.instance_variable_set :@current_index, 0
    singleton.instance_variable_set :@storage, []
  end
  extended self
end