gistfile1.rb

class Roman        
  
  Symbols = { 1=>'I', 5=>'V', 10=>'X', 50=>'L', 100=>'C', 500=>'D', 1000=>'M' }
  Subtractors = [ [1000, 100], [500, 100], [100, 10], [50, 10], [10, 1], [5, 1], [1, 0] ]
  
  def initialize(i)
    @i = i
  end
  
  def to_s
    roman(@i)
  end
  
  def roman(num)
    return Symbols[num]  if Symbols.has_key?(num)
    return '' if num <= 0
    Subtractors.each do |cut_point, subtractor| 
      return roman(cut_point) + roman(num - cut_point)      if num >  cut_point
      return roman(subtractor) + roman(num + subtractor)  if num >= cut_point - subtractor and num < cut_point
    end
  end
  
end                        

if __FILE__ == $0
  num = 8879
  puts "Arabic #{num} in Roman numerals is #{Roman.new(num).to_s}" 
end