module Unicode
  def self.const_missing(name)
    # Check that the constant name is of the right form: U0000 to U10FFFF
    if name.to_s =~ /^U([0-9a-fA-F]{4,5}|10[0-9a-fA-F]{4})$/
      # Convert the codepoint to an immutable UTF-8 string,
      # define a real constant for that value and return the value
      #p name, name.class
      const_set(name, [$1.to_i(16)].pack("U").freeze)
    else  # Raise an error for constants that are not Unicode.
      raise NameError, "Uninitialized constant: Unicode::#{name}"
    end
  end
end