Is it theoretically possible that an interface with a `suspe kotlinlang #coroutines

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Title

m

Matt Groth

05/11/2023, 10:47 PM

Is it theoretically possible that an interface with a

suspend fun

could have a class that implements it and converts it to just a regular

fun

? The implementing class would simply ignore the

suspend

keyword.

k

kevin.cianfarini

05/11/2023, 10:52 PM

Since a continuation is added at compile time to function signatures I doubt it. However I think you've be interested in the research going into Rust to make keywords (like

async

) generic. https://blog.rust-lang.org/inside-rust/2022/07/27/keyword-generics.html

m

Matt Groth

05/11/2023, 10:58 PM

Interesting read, thanks. I suppose there aren’t any KEEPs or youtrack issues where people are discussing a solution specifically for kotlin?

e

ephemient

05/12/2023, 12:31 PM

you can somewhat do this already with

interface Suspending {
    suspend fun get()
}
abstract class Immediate : Suspending {
    abstract fun immediate()
    final override suspend fun get() = immediate()
}

but the two functions need different names (even though technically their platform signatures don't collide)

or if you don't mind being unsafe, a wrapper like

fun <T> runUndispatched(block: suspend () -> T): T {
    val scope = CoroutineScope(Dispatchers.Unconfined)
    val deferred = scope.async { block() }
    scope.cancel()
    return deferred.getCompleted()
}

and as long as

block

returns a value without actually suspending, it'll work (otherwise it'll throw)

w

why

05/27/2023, 8:50 AM

I like this thanks. So sick of the word safe!

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