version.rb

class Version
  attr_reader(:major, :minor, :patch)

  def initialize (version)
    @major, @minor, @patch =
      version.split('.').map(&:to_i)
  end

  def <=> (other)
    return nil unless other.is_a?(Version)

    [ major <=> other.major,
      minor <=> other.minor,
      patch <=> other.patch,
    ].detect {|n| !n.zero?} || 0
  end
end