kotlinx.coroutines.channels.LazyBroadcastCoroutine cannot be cast to kotlinx.coroutines.channels.ConflatedBroadcastChannel

[nbransby]

I would expect this to be a ConflatedBroadcastChannel, in fact I would like an api where I would not have to cast

/** use this to show that at least one other team mate is currently online (or not) */
val indicateOnlne = users.openSubscription()
            .map { it.count { user -> user.online } }
            .map { it > 1 }
            .broadcast(capacity = Channel.CONFLATED) as ConflatedBroadcastChannel

Also in the meantime is there a workaround for creating a ConflatedBroadcastChannel from an existing ReceiveChannel?

[qwwdfsad]

broadcast(capacity = Channel.CONFLATED) behaves like a ConflatedBroadcastChannel but is not an instance of ConflatedBroadcastChannel (and documentation does not guarantee so).
Under the hood, it creates a more efficient version of "launched coroutine + channel" and it implements only BroadcastChannel. It is not easy to make it ConflatedBroadcastChannel as well, because it is a class, not an interface.

Also in the meantime is there a workaround for creating a ConflatedBroadcastChannel from an existing ReceiveChannel?

By manually implementing it with launch coroutine. While it is possible to provide a new API, could you please elaborate why do you need exactly ConflatedBroadcastChannel?

[nbransby]

My use case is to remove the member variable and change this line...

https://github.com/TeamHubApp/intellij-plugin/blob/master/src/main/kotlin/app/teamhub/UserNode.kt#L75

...to....

presentation.presentableText = model.title.value

and documentation does not guarantee so

I suggest you make that clearer in the documentation

kotlinx.coroutines/common/kotlinx-coroutines-core-common/src/channels/Broadcast.kt

Line 49 in d6a5a39

* * when `capacity` is [CONFLATED] -- uses [ConflatedBroadcastChannel] that conflates back-to-back sends;

[qwwdfsad]

As a temporary workaround you can use model.title.poll ?: error("...")

[nbransby]

Thanks for the workaround I added:

val <E> BroadcastChannel<E>.value get() = openSubscription().poll()!!

in anticipation of a being able to use a real ConflatedBroadcastChannel sometime in the future!

[qwwdfsad]

Broadcast channels are obsolete and will be superseded by the corresponding Flow primitives, so closing as "won't fix"