> Le 4 sept. 2017 à 10:01, Wallacy via swift-evolution
> <[email protected]> a écrit :
>
> func processImageData1a() async ->
> Image {
> let dataResource = async loadWebResource("dataprofile.txt")
> let imageResource = async loadWebResource("imagedata.dat")
>
> // ... other stuff can go here to cover load latency...
>
> let imageTmp = await decodeImage(dataResource, imageResource) //
> compiler error if await is not present.
> let imageResult = await dewarpAndCleanupImage(imageTmp)
> return imageResult
> }
>
>
> If this (or something like that) is not implemented, people will create
> several versions to solve the same problem, so that later (Swift 6?) will be
> solved (because people want this), and we will live with several bad codes to
> maintain.
Just to be sure of what you are proposing, am I right to assume this would be
compiled down to something like this?
func processImageData1a(completion: (Image) -> ()) {
var dataResource: Resource? = nil
var imageResource: Resource? = nil
var finishedBody = false
func continuation() {
// only continue once everything is ready
guard finishedBody else { return }
guard dataResource = dataResource else { return }
guard imageResource = imageResource else { return }
// everything is ready now
decodeImage(dataResource, imageResource) { imageTmp in
dewarpAndCleanupImage(imageTmp) { imageResult in
completion(imageResult)
}
}
}
loadWebResource("dataprofile.txt") { result in
dataResource = result
continuation()
}
loadWebResource("imagedata.dat") { result in
imageResource = result
continuation()
}
// ... other stuff can go here to cover load latency...
finishedBody = true
continuation()
}
This seems more lightweight than a future to me. I know I've used this pattern
a few times. What I'm not sure about is how thrown errors would work. Surely
you want error handling to work when loading resources from the web.
--
Michel Fortin
https://michelf.ca
_______________________________________________
swift-evolution mailing list
[email protected]
https://lists.swift.org/mailman/listinfo/swift-evolution
