Hi! I have a class which looks like this ```class MyQueueProcessor: CoroutineScope by CouroutineScop...

# coroutines

[gotoOla]

Hi! I have a class which looks like this

class MyQueueProcessor: CoroutineScope by CouroutineScope(<http://Dispatchers.IO|Dispatchers.IO>) {
    suspend fun start() {
        pollMessages()
        processors.addAll(
            (1..5).map {
                launchMessageProcessor()
            }
        )
    }
    
    suspend fun pollMessages() = launch {
       while(true) {
          val messages = //... get messages from a queue
          internalChannel.send(messages)
       }
    }
    
    suspend fun launchMessageProcessor() = launch {
        for (messages in internalChannel) {
            // process each 'messages'
        }
    }

}

but for both pollMessages and launchMessageProcessor I get "Ambiguous coroutineContext due to CoroutineScope receiver of suspend function". How should I interpret this?

Is it because suspend fun start() is public and you inherit the coroutineContext from the caller? Since I extend CoroutineScope, the launch and async stuff I use should run on that scope with that dispatcher (IO) right?

[dekans]

suspend fun launchMessageProcessor() = launch {} doesn't make sense.
launch is not a suspend function

[dekans]

Either you remove the suspend keyword

[Evan R.]

It is because if someone else is invoking the class functions from their own coroutine scope, it is not clear if the launch should occur in the caller’s coroutine scope or the coroutine scope of the class

[dekans]

Or you remove the launch and launchMessageProcessor becomes a real suspend function

[dekans]

which will have to be started from inside a launch {..}

[dekans]

idem for pollMessages()

[gotoOla]

@dekans ah of course, that's totally unecessary

@Evan R. ah gotcha. = this.launch {...} should clarify that ambigouity if I remove the suspend from the function then, right?

[Evan R.]

Yep!

[gotoOla]

Thanks! 😊