> On Jan 11, 2017, at 2:02 PM, Howard Lovatt via swift-evolution
> <swift-evolution@swift.org> wrote:
>
> Another possibility, other than generics, would be to drop rethrows all
> together and have the compiler infer if a throw is possible or not, including:
>
> struct FStore {
> let f: () throws -> Void
> func call() throws { try f() }
> }
>
> The compiler can make two versions, one if f can throw and one if it
> definitely doesn't.
It seems that this approach is impractical, because you either have to compile
two versions of every function, or make all function bodies available for
inlining, which is a non-starter for a stable ABI.
Slava
>
> Just a thought.
>
> On Tue, 10 Jan 2017 at 4:29 pm, Jacob Bandes-Storch <jtban...@gmail.com
> <mailto:jtban...@gmail.com>> wrote:
> Moving to swift-users list.
>
> No, there's no way to do this today. The point of rethrows is that within one
> call site, "f(block)" can be treated as throwing if the block throws, or not
> throwing if the block doesn't throw. In your example, once the FStore object
> is constructed, the information about the original passed-in function is
> lost, so the caller has no way to know whether call() can throw or not.
>
> If this *were* possible, the information would somehow need to be encoded in
> the type system when creating FStore(f: block). That would require something
> like dependent typing, or generic-param-based-rethrows, e.g.
>
> struct FStore<T: () throws -> Void> { // made-up syntax
> let f: T
> func call() rethrows(T) { try f() } // throws-ness of this function
> depends on throws-ness of T
> }
>
>
>
> On Mon, Jan 9, 2017 at 9:21 PM, Howard Lovatt via swift-evolution
> <swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote:
> Hi,
>
> If I have an escaping function that I store and then call, I need to declare
> the calling function as throwing, not rethrowing. EG:
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> struct FStore {
> let f: () throws -> Void
> init(f: @escaping () throws -> Void) { self.f = f }
> func call() throws { try f() } // Can't put rethrows here - have to
> use throws
> }
>
> Is there a better solution?
>
> Thanks for any suggestions,
>
> -- Howard.
>
>
>
>
>
> _______________________________________________
>
>
> swift-evolution mailing list
>
>
> swift-evolution@swift.org <mailto:swift-evolution@swift.org>
>
>
> https://lists.swift.org/mailman/listinfo/swift-evolution
> <https://lists.swift.org/mailman/listinfo/swift-evolution>
>
>
>
>
>
>
> --
> -- Howard.
> _______________________________________________
> swift-evolution mailing list
> swift-evolution@swift.org <mailto:swift-evolution@swift.org>
> https://lists.swift.org/mailman/listinfo/swift-evolution
> <https://lists.swift.org/mailman/listinfo/swift-evolution>
_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution
