Hi, I want to tranform a flow to a disposable/closeable value and automatically close/dispose each t...

# coroutines

[Philipp Kleber]

Hi, I want to tranform a flow to a disposable/closeable value and automatically close/dispose each transformed value as soon as a new value is emitted or the flow completes. I have come up with the following implementation of this behavior:

@OptIn(ExperimentalCoroutinesApi::class)
inline fun <T, S> Flow<T>.mapDisposable(
    crossinline transform: suspend (value: T) -> S,
    crossinline onDispose: (S) -> Unit
) : Flow<S> {
    return flatMapLatest { value ->
        callbackFlow {
            val transformed: S = transform(value)
            trySend(transformed)
            awaitClose {
                onDispose(transformed)
            }
        }
    }
}

Is there a better or even a built-in way for achieving this?

[Nick Allen]

Are you aware that the code using your disposable item may not be done with it. flatMapLatest uses a channel so the collector is in a different coroutine than the callbackFlow lambda. Also, flatMapLatest may cancel collecting from the Flow but it has no effect on any coroutines running based on already emitted values.