Multiple invocations of `on-finished`

[dazld]

I'm not sure what the correct behaviour should be here, but might be worth thinking about a little.

Given the following code:

(let [now (Instant/now)
        chiming (chime/chime-at [(.plusSeconds now 1)
                                 (.plusSeconds now 3)]
                                (fn [time]
                                  (prn :chime (str time)))
                                {:on-finished #(prn :done)})]
    (Thread/sleep 4000)
    (.close chiming))

... we can see that on-finished is called twice:

:chime "2020-09-07T13:52:33.193745Z"
:chime "2020-09-07T13:52:35.193745Z"
:done
:done

This was surprising to me - perhaps on-finished should have an invariant that it is only ever called once?

Another option is that perhaps the value which on-finished evaluates to should be delivered to the invocation of close, meaning the fn can be evaluated once, but value delivered to multiple places...? Seems like this could be useful.

[jarohen]

Thanks @dazld, will have a look 😄

[jarohen]

This was surprising to me - perhaps on-finished should have an invariant that it is only ever called once?

agreed!

Another option is that perhaps the value which on-finished evaluates to should be delivered to the invocation of close

Unfortunately .close is from java.io.Closeable, which returns void, so we can't do this. Reckon it's simple enough to achieve outside Chime - with a separate promise, maybe?

Cheers for raising the issue 😄