derivatives unavailable in `will-unmount` if the latter is placed after the former.

[livtanong]

Affects get-ref.

If I understand the source correctly, this is because the derivatives mixin always includes unmount code. You can call the custom will-unmount before the derivatives mixin, but as a project gets more complex, it could lead to code that is difficult to reason about. Something more explicit could be worth exploring.

I have two suggestions:

1. Split the derivatives mixin into separate mount and unmount functions/vars
2. Include an optional will-unmount hook into the d/drv mixin that will get called before the mixin executes its own unmount.

[martinklepsch]

Can you maybe add a code snippet that illustrates the problem? :)

On Mon, Jun 5, 2017, 23:15 Levi Tan Ong [email protected] wrote:

Affects get-ref.

If I understand the source correctly, this is because the derivatives mixin always includes unmount code. You can call the custom will-unmount before the derivatives mixin, but as a project gets more complex, it could lead to code that is difficult to reason about. Something more explicit could be worth exploring.

I have two suggestions:

1. Split the derivatives mixin into separate mount and unmount functions/vars
2. Include an optional will-unmount hook into the d/drv mixin that will get called before the mixin executes its own unmount.

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[livtanong]

Sorry for taking so long, I've been quite busy these past few days.

(defcs sample
  <
  rum/reactive
  (d/drv :app/data)
  #?(:cljs
     {:will-mount (fn [state]
                    ;; we have access to derivatives
                    state)
      :will-unmount (fn [state]
                      ;; no access to derivatives
                      state)})
  [state]
  nil)