[swift-evolution] Question about async await

[Adam Kemp]

> On Sep 25, 2017, at 3:04 PM, Jean-Daniel via swift-evolution <swift-evolution at swift.org> wrote:
> 
>> Le 25 sept. 2017 à 21:42, John McCall via swift-evolution <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> a écrit :
>> 
>> This doesn't have to be the case, actually.  The intrinsics as Chris described them wouldn't be sufficient, but you could require a "current queue" to be provided when kicking off an async function from scratch, as well as any other "async-local" context information you wanted (e.g. QoS and the other things that Dispatch tracks with attributes/flags that are generally supposed to persist across an entire async operation).
>> 
> 
> My response was about the ‘implicitly’ part. I hope we will get a rich API that let us specify return queue, QoS and more, but how do you plan to fulfill the « current queue » requirement implicitly ?

My earlier response to this thread both linked to a previous thread about this and explained how C# does it. It will require some library support, but it can be done, and IMO should be done. As I’ve stressed repeatedly, async/await without this behavior will be very difficult to use correctly. I really hope we don’t settle for that.
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