Playing with ObjectSpace and GC

test.rb

class Vehicle
  class << self
    attr_accessor :count
    def finalize(id)
      @count -= 1
    end

    def all #returns an array of all Vehicle objects
      ObjectSpace.each_object(Vehicle).to_a
    end
  end
  Vehicle.count ||= 0

  def initialize
    Vehicle.count += 1
    ObjectSpace.define_finalizer(self, Vehicle.method(:finalize))
  end
end

arr = []
100.times { arr << Vehicle.new }
arr.each do |a|
   arr.delete(a)
end
arr.size #=> Raz zostaje 25, raz 50...