Do we support where clauses on these existentials? For example, can I write:
func doSomething<T>(_: NSObject & Collection where Iterator.Element == T) The proposal says nothing about where clauses. - Karl > > On Mar 20, 2017 at 7:00 pm, <Douglas Gregor via swift-evolution > (mailto:[email protected])> wrote: > > > > > Proposal link: > > > > > > https://github.com/apple/swift-evolution/blob/master/proposals/0156-subclass-existentials.md > > > > > > > > > > Hello Swift community, > > > > The review of SE-0156 “Class and Subtype Existentials” ran from February > 28...March 7, 2017. The proposal was very well-received and is accepted > with one modification: the ordering rules for existential types that involve > AnyObject or a class type will be removed. > > > The ordering rules were intended to improve code clarity by requiring that > the class (or AnyObject) constraint come first—“AnyObject & P” would be > well-formed but “P & AnyObject” would be an error—enforcing more > uniformity for Swift code and echoing a similar restriction that already > exists for class definitions, where the superclass must come first. However, > the ability to compose typealiases complicated the ordering rules > considerably, and—as noted by Matthew Johnson > (https://lists.swift.org/pipermail/swift-evolution/Week-of-Mon-20170227/033365.html)—don’t > provide the guarantee that the class constraint will always be first. > Therefore, the core team felt that the resulting ordering rules introduced > more complexity than they provided clarity, and therefore do not belong in > the language. > > > > Thanks, > > Doug Gregor, Review Manager > > > _______________________________________________ swift-evolution mailing list > [email protected] > https://lists.swift.org/mailman/listinfo/swift-evolution
_______________________________________________ swift-evolution mailing list [email protected] https://lists.swift.org/mailman/listinfo/swift-evolution
