triangle.rb

class TriangleError < Exception
end

class Triangle

  def initialize(side1, side2, side3)
    @side1=side1
    @side2=side2
    @side3=side3
    triangle?
  end

  def kind
    return :equilateral if (@side1==@side2)&&(@side2==@side3)
    (@side1==@side2)||(@side2==@side3)||(@side1==@side3) ? :isosceles : :scalene
  end

  def triangle?
      sides=[@side1, @side2, @side3].sort!
      if sides[2]<sides[1]+sides[0] && sides[0]>0
      else
        raise Exception::TriangleError
      end       
  end
end