gistfile1.txt

class Tracker
  @tracked_items = []
  
  def initialize
    Tracker.tracked_items << self
  end
  
  def self.tracked_items
    @tracked_items
  end
end

class Tracked < Tracker
  def initialize
    super
  end
end

x = Tracked.new
y = Tracked.new
p Tracker.tracked_items