My 99 Bottles solution with refactoring, memoization, and six-pack feature

bottles.rb

class Bottles
  def song
    verses 99, 0
  end

  def verses high, low
    high.downto(low).map { |count| verse count }.join "\n"
  end

  def verse count
    "#{container(count).capitalize} of beer on the wall, "\
    "#{container(count)} of beer.\n"\
    "#{action(count)}, #{container(successor(count))} of beer on the wall.\n"
  end

  private

  def container count
    unless @containers
      @containers = Hash.new { |hash, key| "#{key} bottles" }
      @containers[6] = '1 six-pack'
      @containers[1] = '1 bottle'
      @containers[0] = 'no more bottles'
    end

    @containers[count]
  end

  def action count
    unless @actions
      @actions = Hash.new 'Take one down and pass it around'
      @actions[1] = 'Take it down and pass it around'
      @actions[0] = 'Go to the store and buy some more'
    end

    @actions[count]
  end

  def successor count
    count > 0 ?	count -	1 : 99
  end
end