module Color
  Red = 1
  Green = 2
  Blue = 3
  Rgb = Struct.new(:r, :g, :b)
end

color = Color::Rgb.new(255, 255, 255)
puts case color
when Color::Red; "#FF000"
when Color::Green; "#00FF00"
when Color::Blue; "#0000FF"
when Color::Rgb; "#%02X%02X%02X" % [color.r, color.g, color.b]
end