Metaprogramming Ruby 2

Singleton Methods

Where it’s your turn to teach Bill a few tricks.

It’s late morning, and you and Bill are deep in the flow. You’re zipping through the Bookworm source, deleting a useless line here, changing a confusing name there, and generally polishing the code…until you bump into a particularly troublesome bit of refactoring.

The Paragraph class wraps a string and then delegates all calls to the wrapped string—all of them, that is, except for one method, Paragraph#title?, which returns true if a Paragraph is all uppercase.

class_definitions/paragraph.rb

class Paragraph
  def initialize(text)
    @text = text
  end

  def title?; @text.upcase == @text; end
  def reverse; @text.reverse; end
  def upcase; @text.upcase;  ...