Extend protocol in ClojureScript to get value from native js object

Question

I have a codebase that makes a heavy use of get and get-in for nested forms. I want to be able to use native javascript objects too, without (much) code rewrite.

js> cljs.user.o = {foo: 42}  // in js console

cljs.user> (get o "foo") ; => 42 ; in cljs console

Since I only query the forms, but don't modify them, I thought it would be enough to implement get (which get-in relies on). Here is my attempt,

(extend-protocol ILookup
  js/Object
    (-lookup [m k] (aget m k))
    (-lookup [m k not-found (or (aget m k) not-found)))

It seems to work, but it breaks a lot of things in a strange way.

WW. · Accepted Answer · 2013-11-21 23:51:12Z

10

You're modifying the Object prototype, you don't want to do that, the following is better:

(extend-protocol ILookup
  object
  (-lookup [m k] (aget m k))
  (-lookup [m k not-found] (or (aget m k) not-found)))

edited Nov 21, 2013 at 23:51

WW.

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answered Jun 3, 2013 at 19:17

dnolen

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1 Comment

Adi Inbar Over a year ago

@tomconnors No need to add text for reviewers to remove; you can just add some  s

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