Convert Unicode codepoints to UTF-8 characters with Module#const_missing

ntk () — Sat, 15 Sep 2007 12:25:16 GMT

From: http://www.davidflanagan.com/blog/2007_08.html#000136
Author: David Flanagan





# This module lazily defines constants of the form Uxxxx for all Unicode

# codepoints from U0000 to U10FFFF. The value of each constant is the

# UTF-8 string for the codepoint.

# Examples:

#   copyright = Unicode::U00A9

#   euro = Unicode::U20AC

#   infinity = Unicode::U221E

#

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





puts copyright = Unicode::U00A9

puts euro = Unicode::U20AC

puts euro = Unicode::U20AC

puts infinity = Unicode::U221E

puts Unicode.const_get(:U221E)

p Unicode.constants

puts Unicode.constants

Unicode.constants.each { |u| puts Unicode.const_get(u) }

DZone Snippets: codepoint code

Convert Unicode codepoints to UTF-8 characters with Module#const_missing