Might I add that leaving an array in an arbitrary and implementation-dependent state is also surprising to users as well as not very useful-to the user this is nothing more than a random permutation.
On Mon, Jun 6, 2016 at 5:31 PM Dave Abrahams via swift-evolution < swift-evolution@swift.org> wrote: > > on Sun Jun 05 2016, Haravikk <swift-evolution@swift.org> wrote: > > >> On 5 Jun 2016, at 19:14, Tim Vermeulen via swift-evolution < > swift-evolution@swift.org> wrote: > >> > >> Most standard library functions that take a closure allow that > >> closure to throw (and those functions are subsequently marked with > >> rethrows). sort and sorted are exceptions to this. I couldn’t find > > > >> this documented anywhere, but I assume this is because sorting can > >> happen in-place and it would be impossible to restore the array to > >> its original state without giving up performance. Correct me if I’m > >> wrong. > >> > >> I’d like to propose that we let sort rethrow anyways, and leave the > >> array in an intermediate state (where the elements are in an > >> arbitrary order) when an error is thrown. As long as this is > >> properly documented, this shouldn’t lead to any confusion. Best of > >> all, it would allow sorted to rethrow as well in which there is no > >> room for confusion at all because it doesn’t mutate any of the > >> user’s variables. > > > > This sounds reasonable; worst case with in-place sorting is that the > > collection was sorted in one order, and is only partially sorted in a > > new one, but the exception and your handling of it should be able to > > account for this. > > > > It will require documentation to be clear that sorting methods should > > take care not to leave anything incomplete if a closure throws; most > > algorithms should be fine since they usually just test the closure > > then swap two values afterwards (where necessary) so there’s nothing > > really to interrupt, but anything that uses some kind of buffering may > > need to be redesigned to ensure there’s a fallback to ensure no > > elements are ever lost. > > Ensuring that no elements are ever lost is not a particularly useful > goal, and not a constraint to which I would want to hold the standard > library. > > -- > Dave > > _______________________________________________ > swift-evolution mailing list > swift-evolution@swift.org > https://lists.swift.org/mailman/listinfo/swift-evolution > -- -Saagar Jha
_______________________________________________ swift-evolution mailing list swift-evolution@swift.org https://lists.swift.org/mailman/listinfo/swift-evolution
