Kotlin coroutines handle error and implementation

Question

Using coroutines for the first time. Need help.

Here is my flow:

Presenter wants to login so calls Repository Interface. Repository implements RepositoryInte

Answer 1

EDIT:

I am trying this solution in my new app and i released that if an error occurs in launchSafe method and try to retry request, launcSafe() method does not work correctly. So i changed the logic like this and problem is fixed.

fun CoroutineScope.launchSafe(
    onError: (Throwable) -> Unit = {},
    onSuccess: suspend () -> Unit
) {
   launch {
        try {
            onSuccess()
        } catch (e: Exception) {
            onError(e)
        }
    }
}

OLD ANSWER:

I think a lot about this topic and came with a solution. I think this solution cleaner and easy to handle exceptions. First of all when use write code like

fun getNames() = launch { }  

You are returning job instance to ui i think this is not correct. Ui should not have reference to job instance. I tried below solution it's working good for me. But i want to discuss if any side effect can occur. Appreciate to see your comments.

fun main() {


    Presenter().getNames()

    Thread.sleep(1000000)

}


class Presenter(private val repository: Repository = Repository()) : CoroutineScope {

    private val job = Job()

    override val coroutineContext: CoroutineContext
        get() = job + Dispatchers.Default // Can be Dispatchers.Main in Android

    fun getNames() = launchSafe(::handleLoginError) {
        println(repository.getNames())
    }
    

    private fun handleLoginError(throwable: Throwable) {
        println(throwable)
    }

    fun detach() = this.cancel()

}

class Repository {

    suspend fun getNames() = suspendCancellableCoroutine> {
        val timer = Timer()

        it.invokeOnCancellation {
            timer.cancel()
        }

        timer.schedule(timerTask {
            it.resumeWithException(IllegalArgumentException())
            //it.resume(listOf("a", "b", "c", "d"))
        }, 500)
    }
}


fun CoroutineScope.launchSafe(
    onError: (Throwable) -> Unit = {},
    onSuccess: suspend () -> Unit
) {
    val handler = CoroutineExceptionHandler { _, throwable ->
        onError(throwable)
    }

    launch(handler) {
        onSuccess()
    }
}