normalising-access-to-values.cljs

(defprotocol IClear
  (clear! [x]))

(defn field-as-value [field-cursor]
  (reify
    IDeref
    (-deref [_] (:value field-cursor))
    ISwap
    (-swap! [o f] (reset! o (f @o)))
    (-swap! [o f a] (reset! o (f @o a)))
    (-swap! [o f a b] (reset! o (f @o a b)))
    (-swap! [o f a b xs] (reset! o (apply f @o a b xs)))
    IReset
    (-reset! [o new-value] (om/update! field-cursor :value new-value))
    IClear
    (clear! [_] (om/transact! field-cursor :value (:initial field-cursor)))))

(defn state-as-value [owner key]
  (reify
    IDeref
    (-deref [_] (om/get-state owner key))
    ISwap
    (-swap! [o f] (reset! o (f @o)))
    (-swap! [o f a] (reset! o (f @o a)))
    (-swap! [o f a b] (reset! o (f @o a b)))
    (-swap! [o f a b xs] (reset! o (apply f @o a b xs)))
    IReset
    (-reset! [o new-value] (om/set-state! owner key new-value))
    IClear
    (clear! [_] (om/set-state! owner key nil))))