color-string.rb

class ColorString < String
  COLORS = {
    black:   30,
    red:     31,
    green:   32,
    yellow:  33,
    blue:    34,
    magenta: 35,
    cyan:    36
  }

  def initialize(string, color)
    raise NotImplementedError, "#{color} strings are not supported" if COLORS[color].nil?

    super("\e[#{COLORS[color]}m#{string}\e[0m")
  end
end