how would I turn this into something that uses coroutines ``

Question

how would I turn this into something that uses coroutines ```class DetermineAuthStatus Inject constructor private val firebaseAuth FirebaseAuth private val populateUserPrefs PopulateUserPrefs operator fun invoke = firebaseAuth currentUser let currentUser gt val subject = SingleSubject create lt Boolean gt subject hide doOnSubscribe currentUser getIdToken false addOnSuccessListener task gt populateUserPrefs currentUser task token subject onSuccess true addOnFailureListener subject onError it Single just false ```

Rick Clephas · Answer

You could use `suspendCoroutine` <https kotlinlang org api latest jvm stdlib kotlin coroutines suspend coroutine html> Something like ```val currentUser = firebaseAuth currentUser return false suspendCoroutine cont gt currentUser getIdToken false addOnSuccessListener task gt populateUserPrefs currentUser task token cont resume true addOnFailureListener cont resumeWithException it ```

oday · Answer

well thank you very much for scrolling up and finding this and taking the time to answer it I will be looking at it tonight and seeing how it behaves thanks a lot

oday · Answer

ok so I m just looking at it now and I have some questions it looks like this shape or way of doing it can be suitable for all my usecases that just go out and do something and return something else depending on what it found or is this something specific to what you saw the original code was doing how do I treat this back in where i want to invoke it ```val authenticated = determineAuthStatus invoke if authenticated do something else do something else ``` what about when it s an exception instead of the boolean im expecting do I just place it in a try catch all the time to make sure i catch these exceptions

Rick Clephas · Answer

gt it looks like this shape or way of doing it can be suitable for all my usecases that just go out and do something and return something else depending on what it found or is this something specific to what you saw the original code was doing Yeah correct you can use `suspendCoroutine` to convert any kind of single result callback to a suspend function gt how do I treat this back in where i want to invoke it What do you mean exactly gt what about when it s an exception instead of the boolean im expecting gt do I just place it in a try catch all the time to make sure i catch these exceptions It depends on the use case you could return the exception from your suspend function In that case you should pass it to the `resume` call Or you could return `Unit` and have the function throw the exception like in my previous example

oday · Answer

your function actually does the first suggestion pass it to the resume call

Rick Clephas · Answer

In this case it uses `resumeWithException` which will throw the exception So you should wrap the call in a try catch to handle them

oday · Answer

clear and that s not like ugly or anything I see it s perfectly fine to do this honestly having the try catch at the call place instead of where the value is received

Rick Clephas · Answer

I don t think it s ugly That said there might be a more elegant way to do this but that depends on what you are trying to accomplish and from where you are going to use this function

oday · Answer

well it s just inside the viewmodel for the main screen if the user turns out to be authenticated show the home screen otherwise show the auth screen sign in sign up

Rick Clephas · Answer

In that case I would probably just log the exception and resume with `false`

oday · Answer

makes sense

oday · Answer

by the way I am reading a really great book by Raywenderlich called Kotlin Coroutines by Tutorials super well written and thorough I just reached `suspendCoroutine` which you gave me the shortcut to slightly smiling face