Alternative to http://squirrel.pl/blog/2013/01/16/clojurescript-painkiller-for-oop/ using protocols

bag.cljs

;; response to http://squirrel.pl/blog/2013/01/16/clojurescript-painkiller-for-oop/

(defn Bag []
  (this-as this
    (set! (.-store this) (array))
    this))

(defprotocol MyBag
  (add [this val])
  (print [this]))

(extend-type Bag
  MyBag
  (add [this val]
    (.push (.-store this) val))
  (print [this]
    (.log js/console (.-store this))))

(def mybag (Bag.))
(add mybag 2)
(add mybag 3)
(print mybag)
;;> [2, 3]