A class that implements cyclic array in Ruby

cyclic_array.rb

class CyclicArray
  include Enumerable

  attr_reader :a

  def initialize(a = [])
    raise ArgumentError unless a.respond_to? :each

    @a = a
  end

  def [](n)
    chunks = (n.abs / a.length).next
    a.cycle(chunks).to_a[n]
  end

  private

    def method_missing(name, *args, &block)
      case
      when a.cycle.respond_to?(name)
        a.cycle.send(name, *args, &block)
      when a.respond_to?(name)
        a.send(name, *args, &block)
      else
        super
      end
    end
end