reagent 2022-04-14 | Slack Archive

Pepijn de Vos09:04:28

With a from-2 component, what's the significance of the arguments of the inner and outer function? I think the docs tell you that they should be the same, but I've seen code where the inner just did not take arguments.

vanelsas10:04:38

The outer function sets the arguments upon entry, the inner function sets them on rerender?

Pepijn de Vos10:04:36

Yea but what happens when the list of arguments is not the same?

vanelsas10:04:41

basically you would lose the ability to update an argument in a rerender. If I add an extra argument on the outer function but not in the rerender function it will not update in the rerender I guess. Not an expert.

Pepijn de Vos10:04:24

Mostly what I've seen is where the inner fn just takes no args... maybe that's valid if you only use the args in the outer fn? not sure

vanelsas10:04:18

well

vanelsas10:04:44

here is a scenario that would fail I think

(defn wont-update [x]
  (let [] ;; here you would prob declare some inner state with an r/atom
    (fn []
      (println x))))

;; (wont-update 3) -> 3
;; (let [input (r/atom 2)]
     (wont-update @input) ;; -> 2
     (reset! input 5)
     (wont-update @input) ;; -> 2

Pepijn de Vos10:04:07

Yea using x in the inner fn while not passing it to the inner function is clearly wrong.

snoe16:04:34

with-let helps a lot to unify the args.

Leif20:04:16

Anyone aware of any good patterns/libraries for partitioning a map (example with a reagent element)

(defn my-element [{:keys [key1 key2] :as props} & children]
   ; Do stuff with key1 and key2

   ; Pass down remaining props to :div
   [:div (dissoc props :key1 :key2) ...])

Wanted to ask before I write my own defn wrapper macro that has support for something like [{:keys [key1 key2] :as props :remaining other-props} ...}

p-himik20:04:36

Please avoid cross-posting. There are almost 10x as many people in #clojurescript and I'd say your question belongs more to #clojure even because it's really generic.

2022-04-14

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