1- Don't macro this, we do not promise to keep this working. Write it out each time 2- we want to understand what circumstance you're encountering that makes you reach for this, so we can solve it in a better way

Search "causal" for past discussions

Basically just flipping some CSS classes.

(cause
  (reset! processing-atom true)
  (transact-some-stuff-to-server …)
  (reset! processing-atom false))

Does this idiom solve your problem https://electric.hyperfiddle.net/user.demo-chat!%43hat

(catch Pending e (dom/style {:background-color "yellow"}))

The stuff I need to control sits in an awkward place, which is why I’m proxying status to an atom. Will true in the try and false in a finally do the trick?

i'm not sure that finally makes sense in electric

you can e/on-unmount in the catch body

Ah, that might be better then. I’ll give it a whirl.

This does not work:

(try
  (reset! processing-atom true)
  (when-let [atom-ident (e/server (e/offload #(create-new-atom node current-space prototype account)))]
    (router/route-to-entity! atom-ident))
  (catch Pending _
    (e/on-unmount #(reset! processing-atom false))))

first, put the reset! inside the pending body

Ah

i dont know why it doesn't work though

(let [load-state (try (e/server ...) ::done (catch Pending _ ::pending))] ...) is maybe a useful idiom

More context:

(dom/on "click"
  (e/fn [_evt]
    (try
      (when-let [atom-ident (e/server (e/offload #(create-new-atom node current-space prototype account)))]
        (router/route-to-entity! atom-ident))
      (catch Pending _
        (reset! processing-atom true)
        (e/on-unmount #(reset! processing-atom false))))))

This sets the atom to false initially, but does nothing else, it seems.

(e/fn [_evt]
  (reset! processing-atom
    (try (e/server (e/offload #(create-new-atom node current-space prototype account)))
      false
      (catch Pending _ true))))

try outside of dom/on (we don’t like dom/on it is dying after differential electric lands)

This works:

(case (helpers/on! "click")
  (reset! processing-atom
    (try (e/server (e/offload #(create-new-atom node current-space prototype account)))
      false
      (catch Pending _ true))))

(defmacro on!
  ([type]
   `(nil->pending (dom/on! ~type identity)))
  ([type f]
   `(nil->pending (dom/on! ~type ~f))))

I think maybe a couple of nested case is a more pragmatic approach at the moment.

what is "dies"

what is "nil->pending"

nil->pending: (if (nil? value) (Failure. (Pending.)) value)

i dont understand why you would artifically throw pending here

and (Failure. (Pending.)) is i think not what you want it to be. You need to throw

Right, I’m reaching the limits of my understanding here. The goal is just to prevent triggering the else case of case on boot, after putting the work outside of on!.

(when click-event ...) ?

Oh yeah, I’m over engineering

Like the one above, this works, but only once. The true branch of when won’t execute again for another truthy value, I presume.

(when (dom/on! "click" identity)
  (reset! processing-atom
    (try (e/server (e/offload #(create-new-atom node current-space prototype account)))
      false
      (catch Pending _ true))))

dom/on manages the pending, if you catch it and don't rethrow it'll do weird stuff. I think you want

dom/on click
  reset! atom true
  e/server ...
  e/on-unmount reset! atom false

No try catch

Works

Nice, I’ll skip the case stuff then. I’m a little bit disappointed that I couldn’t get the “inverted” layout to work. But I’ve been there and failed previously as well.

I think ui5 will solve that. Until then we have to stick with what works

there's a special calva command happening here right?

run it line by line (tap becomes println), or run the whole test

i'm not sure what you're seeing, i will try to find out

running partial tests with the special calva command is going to leak processes, you must cancel each process

Yeah, if run them one by one or all of them, then it behaves as I expected.

Dustin, this calva command to eval, once you get used to it, you start using it so often, it’s so productive. Worth getting used to it. Here are the variants.

@U0ETXRFEW i can't repro the 45350

I used eval from start of toplevel form to cursor

I can’t reproduce it either. But I had been doing eval to cursor a lot of times before that, so maybe that is how to repro. (If the repro is any interesting, and simply not just a non supported use.)

i just wanted to improve the tutorial

pez discovers electric, 楽しみ！ (Looking forward to these discoveries)

sad I missed it, looking forward to watching the recording

That link no longer works but this one does: https://www.youtube.com/watch?v=xtTCdT6e9-0

(e/defn TagItem [id]
  (e/server
    (let [e (xt/entity db id)
          xt-id   (:xt/id e)
          author (:tag/minted-by e)
          tag-id (:tag/id e)
          tag-minted-at (:tag/minted-at e)
          title (:tag/title e)
          target-id (:tag/target e)
          upvotes-set (:tag/upvotes-set e)
          upvotes (:tag/upvotes e)
          downvotes-set (:tag/downvotes-set e)
          downvotes (:tag/downvotes e)
          u (if (not= "" online-user) online-user nil)
          vw true]
      (e/client
        (dom/div (dom/props {:class "fr"})
          (dom/div (dom/props {:class "fc"}))
          (dom/div (dom/props {:class ["fc" "atag"]})
            (dom/div (dom/props {:class "upvote-tag"})
             (if (not (nil? u))
              (ui/button 
                (e/fn [] 
                  (e/server
                    (e/offload
                      #(xt/submit-tx !xtdb 
                                    [[:xtdb.api/put 
                                      (if (and u (contains? upvotes-set u) vw) ;;vw is verified login
                                        ;; user has upvoted, remove their upvote
                                        (-> e
                                            (update :tag/upvotes-set disj u)
                                            (update :tag/upvotes dec))
                                        ;; user hasn't upvoted, include their upvote
                                        (-> e
                                            (update :tag/upvotes-set conj u)
                                            (update :tag/upvotes inc)))]]))))
                (dom/props {:class (if (contains? upvotes-set u) "alreadyupvoted" "notyetupvoted")}) 
                (dom/text "▲ " (count upvotes-set)))
                (dom/div (dom/text "▲ " (count upvotes-set)))))
            (dom/div 
              (dom/props {:class ""}) 
              (dom/text title)))
          (when (= "R" online-user) 
            (dom/div (dom/props {:class "fc"})
              (ui/button 
              (e/fn [] 
                (e/server
                  (let [target-entity (xt/entity db target-id)
                        updated-target (update target-entity :item/tags disj title)]
                    (e/discard
                      (xt/submit-tx !xtdb [[:xtdb.api/put updated-target]
                                          [:xtdb.api/delete xt-id]]))))) 
                    (dom/props {:class "delete"})
                    (dom/text "✗")))))))))

#?(:clj
   (defn tags-for-newsitem [db newsitem-id]
     (->> (xt/q db '{:find [(pull ?t [:xt/id :tag/minted-by :tag/id :tag/minted-at :tag/title :tag/upvotes-set :tag/upvotes])]
                     :where [[?t :tag/target nws-id]]
                     :in [nws-id]} newsitem-id)
       (map first)
       (sort-by :tag/upvotes >)
       vec)))