How do I create an JS Object with methods and constructor in ClojureScript

Question

Imagine the task is to create some utility lib in clojurescript so it can be used from JS.

For example, let's say I want to produce an equivalent of:

    var Foo = function(a, b, c){
      this.a = a;
      this.b = b;
      this.c = c;    
    }

    Foo.prototype.bar = function(x){
      return this.a + this.b + this.c + x;
    }

    var x = new Foo(1,2,3);

    x.bar(3);           //  >>  9    

One way to achieve it I came with is:

    (deftype Foo [a b c])   

    (set! (.bar (.prototype Foo)) 
      (fn [x] 
        (this-as this
          (+ (.a this) (.b this) (.c this) x))))

    (def x (Foo. 1 2 3))

    (.bar x 3)     ; >> 9

Question: is there more elegant/idiomatic way of the above in clojurescript?

Answer 1

This was solved with JIRA CLJS-83 by adding a magic "Object" protocol to the deftype:

(deftype Foo [a b c]
  Object
  (bar [this x] (+ a b c x)))
(def afoo (Foo. 1 2 3))
(.bar afoo 3) ; >> 9

Answer 2

(defprotocol IFoo
  (bar [this x]))

(deftype Foo [a b c]
  IFoo
  (bar [_ x]
    (+ a b c x)))

(def afoo (Foo. 1 2 3))
(bar afoo 3) ; >> 9

Is the idiomatic way to do this.