Kotlinx.coroutines: Deferred.awaitResult()

[hrach]

When I want to make multiple async calls which may fail with fallback, I have to employ some boilerplate code.

supervisorScope {
   val aAsync = async { makeRequest() }
   val bAsync = async { makeAnotherRequest() }
   val a = runCatching { aAsync.await() }.getOrElse { mydefault }
   val b = runCatching { bAsync.await() }.getOrElse { mydefault }
}

I propose adding suspend fun <T> Deferred<T>.awaitResult(): Result<T> for more convenient usage.

val a = aAsync.awaitResult().getOrElse { mydefault }

[hrach]

Should be inner cancellation propagated? /shrug (for usecases when not using supervisorScope)

[elizarov]

As a general primitive, I'm more worried about an outer cancellation. It looks like awaitResult should still throw CancellaationException when the coroutine _it is running in_ is cancelled, but should should wrap and encapsulate the cancellation of the coroutine that it is waiting for.

[fvasco]

I sometimes use:

inline fun <T> CoroutineScope.asyncCatching(crossinline block: suspend () -> T): Deferred<Result<T>> =
    async { runCatching { block() } }

[julioromano]

@fvasco could you please check if https://github.com/Kotlin/kotlinx.coroutines/issues/2130#issuecomment-656605027 works when using the new IR compiler?

I had a very similar instance where it crashed: https://youtrack.jetbrains.com/issue/KT-43536