class NSWTopo::Version

def self.[](creator_string)
  /^nswtopo (?<digit_string>\d+(\.\d+(\.\d+)?)?)$/ =~ creator_string.to_s
  digit_string ? new(digit_string) : raise(Error)
end

def <=>(other)
  self.to_a <=> other.to_a
end

def creator_string
  "nswtopo #{self}"
end

def initialize(digit_string)
  @to_s = digit_string
  @to_a = digit_string.split(?.).map(&:to_i)
end