Bind segment of atom to bindable

[Nikola Vojičić]

I would like to have an atom representing (most of) the UI state.

Values in forms, tabs etc. should change when that atom changes and vice versa.

I'm not sure how to bind UI component to some specific key-value of a nested map inside atom and not to the whole atom.

(def state

  (atom

   {:x 0

    :y "foo"

    :z {:q [1 2 3]

        :w [3 2 1]}}))

I can, for example, bind some input text field to the :y in state via b-swap! with assoc :y, so that it changes the state on input.

But I need bidirectional behaviour - when state :y changes, input text should also be updated.

One way to do that is to wrap each value with an atom:

(def state

  {:x (atom 1)

   :y (atom "foo")

   :z {:q (atom [1 2 3])

       :w (atom [3 2 1])}})

Binding is much simpler now...

(ssb/bind txt (:y state))

(ssb/bind (:y state) txt)

But the state is complex.

Is it thread safe from the Swing point of view?

Application occasionally breaks with the following exception (full stack trace here):

Exception in thread "AWT-EventQueue-0" java.lang.IllegalStateException: Attempt to mutate in notification

at java.desktop/javax.swing.text.AbstractDocument.writeLock(AbstractDocument.java:1349)

at java.desktop/javax.swing.text.AbstractDocument.remove(AbstractDocument.java:590)

at seesaw.bind$eval15943$fn__15948.invoke(bind.clj:167)

at seesaw.bind$eval15805$fn__15806$G__15796__15813.invoke(bind.clj:23)

at seesaw.bind$bind$fn__15868.invoke(bind.clj:88)

at seesaw.bind$eval15911$fn__15912$bindable_atom_watcher__15913.invoke(bind.clj:138)

at clojure.lang.ARef.notifyWatches(ARef.java:81)

at clojure.lang.Atom.reset(Atom.java:157)

at clojure.core$reset_BANG_.invokeStatic(core.clj:2381)

at clojure.core$reset_BANG_.invoke(core.clj:2376)

... even though I am not mutating anything from multiple threads.

[abacus]

Rule of thumb: keep very quiet in the handler of an event from Swing. Instead of causing a ruckus in the handler, use invokeLater to enqueue effects to be done at a time when Swing is not in the event-delivering mode.

[Nikola Vojičić]

Sorry, this exception was caused by my stupid mistake: forgetting to reset the state before running UI from the REPL.

On Thu, Mar 14, 2019 at 9:15 AM abacus <phill...@gmail.com> wrote:

Rule of thumb: keep very quiet in the handler of an event from Swing. Instead of causing a ruckus in the handler, use invokeLater to enqueue effects to be done at a time when Swing is not in the event-delivering mode.

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[Nikola Vojičić]

Also, the second state example (map holding atoms) is not complex at all, atoms are not nested.