You should never extend js/Object.
On Thursday, January 12, 2012, Dave Sann <daves...@gmail.com> wrote:
> code is below.
> Basically - if I extend a protocol on js/Object then I get an error when
calling map on a map with integer keys.
> Is this a bug or an error on my part?
> Cheers
> Dave
> Results first:
> If the extend-protocol and call to 'fred' is commented, ths console shows
> "START"
> "one"
> ([2 1])
> "two"
> "three"
> ([:2 1])
> "four"
> "five"
> ([2 1])
> "done"
> If the extend-protocol and call to 'fred' is uncommented I get:
>
> "START"
> "one"
> ([2 1])
> "two"
> "three"
> ([:2 1])
> "four"
> Uncaught Error: No protocol method ISeqable.-seq defined for type
boolean: true
>
>
>
> Code:
> (ns ptest.main)
>
> (defn map->js [m]
> (let [out (js-obj)]
> (doseq [[k v] m]
> (aset out (name k) v))
> out))
>
> (defn log
> ([x]
> (let [l (if (map? x) (map->js x) x)]
> (.log js/console l)
> x))
> ([m x]
> (do (log {:msg m :data x}) x)))
> (defn log-str
> ([x] (do (log (pr-str x)) x))
> ([m x] (do (log-str {:msg m :data x}) x)))
>
> (log-str "START")
> (defprotocol FRED
> (fred [this] "fred"))
> (log-str "one")
> (log-str
> (map (fn [[k v]] [k v])
> {2 1}))
> (extend-protocol FRED
> js/Object
> (fred [this] this))
> (log-str "two")
> (fred {})
>
> (log-str "three")
> (log-str
> (map (fn [[k v]] [k v])
> {:2 1}))
>
> (log-str "four")
> (def a (doall (map (fn [[k v]] [k v])
> {2 1})))
>
> (log-str "five")
> (log-str a)
>
>
> (log-str "done")
>
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