dicer.rb

class Dicer
  def Dicer.roll(faces, n = 1)
    result = 0
    n.times { result = result + 1 + rand(faces) }
    result
  end
end

class Dice
  attr_reader :faces, :rolls, :result
  def initialize(faces)
    @faces = faces
    @rolls = []
  end
  def roll( n = 1 )
    reset!
    n.times { @rolls << 1 + rand(@faces) }
    @result = @rolls.inject(:+)
  end
  def reset!
    @rolls.clear
    @result = nil
  end
end