fun ReceiveChannel. toDeferred() = async { single() }

, @spierce7 maybe, but probably not such good practice in coroutines to do such a thing though...

why not a good practice to do such a thing?

Coroutines is a whole different way of looking at concurrency, it doesn't need composition as much as Rx, but rather supports linear code just as if there wasn't any concurrency and everything was running on one thread. You shouldn't really need to use Deferred or any coroutine launcher so often, only at the outer level of code, the rest should all be suspend fun... @Jonathan explained this very well in one of the Github coroutine issues, I can't find it right now though 🙁

How would you recommend I do this without using Channel? I need a bridge (similar to rx Subject) between the coroutine world and the non coroutine world:

class AuthWorkflow : AbstractWorkflow<Unit, Unit>() {
  protected val resultChannel = Channel<Unit>()
  
  override fun start(input: Unit): Deferred<Unit> {
    return resultChannel.toDeferred()
  }
  
  override fun abort() {
  }
  
  fun finish() {
    resultChannel.offer(Unit)
  }
}

You need this to be called in Java? Otherwise, you could make

start

into a

suspend fun

and call

single()

or

receive()

. The Channel is fine, the deferred might not be necessary...

because the result won't return until a later time.

It doesn't matter that the result is not till later, it'll suspend just as long as whatever you're calling that needs to be waited for is adapted to suspend too... @spierce7

Can you show me in code? How would I have that function suspend, and then stop from suspending when the result is there?

What do you need to wait for in there @spierce7 ?

So it's probably in most cases awaiting user input. In the case of the AuthWorkflow, the

start

function is called when the user first goes to the auth / login page, and the

Deferred

that will return from it will complete when the user successfully logs in

You're on Android using a WebView? Or using an httpclient to log in? If so, one of them should have a callback you can wrap into a

suspend fun login()

function...

no, I'm not using a webview.

so you don't need a whole class for login... nor a callback.. you just call

login()

as if it would return right away and let it suspend until the result comes in, the next steps will be stored in a continuation until the result arrives, and then the code continues

no

So what is it? Any lib. you can point to?

no, home grown lib

How do you get a result? With a callback?

and

start

returns a

Deferred

, and that

Deferred

, won't complete until after the user has successfully logged in

How do you get the Deferred? Where is it coming from? You need to go to the root to see if it can be turned into a suspend fun...

That's what I'm trying to figure out. Where does the deferred come from? The only way I've found to do it is to take a channel, and then have it return a deferred

Yes,

CompletableDeferred

. But you need to call it from some callback or something...

CompletableDeferred

is exactly what I need

Deferred can also used when you need to run blocking api in

async(MyThreadPool) { ... }

and you get a Deferred as a result

thanks 🙂

Good luck 😉