> On Jun 19, 2017, at 5:23 PM, Brett Walker via swift-users > <swift-users@swift.org> wrote: > > Hi all, > > In the Swift 4 Keypaths proposal [0161] there seem to be several types that > are unimplemented (or not working as I expect them to), and I'm not sure > whether these are simply unfinished in Beta 1, or just ideas that weren't > accepted. > > For instance, according to the proposal AnyKeyPath is supposed to be fully > type-erased and access properties as optionals at run-time, but using it I > only get the compile-time error "Type "FooClass" has no subscript members", > even when applied to objects that still have the original type of the > KeyPath's root. > > Even if I use PartialKeyPath<Root> I get the same error: > -- > var tester = TestClass(name: "steve") > let tester_path = \TestClass.name > > let partial_path:PartialKeyPath<TestClass> = tester_path > let name = tester[keyPath: partial_path] /// no subscript members error here > -- > > Only when I either use the original path variable, or cast it to > KeyPath<TestClass, String>, am I able to access the property without an > error. I am wanting to use KeyPaths in a more generic way, so the AnyKeyPath > and PartialKeyPath would be helpful. Does anyone have insight into the status > of these KeyPath types?
Support for these did not make it into Xcode 9 beta 1. They are available in swift.org snapshot toolchains, if you want to experiment with them now, and should be in a future seed of Xcode 9. -Joe _______________________________________________ swift-users mailing list swift-users@swift.org https://lists.swift.org/mailman/listinfo/swift-users
