Container pattern

container.rb

module Container
  # Initialized once (kind'a singleton)
  def self.a
    @a ||= Object.new
  end
  
  # Initialized every time.
  def self.b
    Object.new
  end
  
  # Initializd once a thread (kind'a threaded singleton)
  def self.c
    Thread.current[:c] ||= Object.new
  end
end

Container.a.object_id #=> 70330567805800
Container.a.object_id #=> 70330567805800

Container.b.object_id #=> 70330563636160
Container.b.object_id #=> 70330563591780

Container.c.object_id #=> 70330567855620
Thread.new { 
  Container.c.object_id #=> 70330563509440
  Container.c.object_id #=> 70330563509440
}