> On Jan 10, 2018, at 12:04, Jose Cheyo Jimenez via swift-evolution > <swift-evolution@swift.org> wrote: > > > > On Tue, Jan 9, 2018 at 10:10 PM, Chris Lattner <clatt...@nondot.org > <mailto:clatt...@nondot.org>> wrote: > On Jan 9, 2018, at 3:07 PM, Jose Cheyo Jimenez <ch...@masters3d.com > <mailto:ch...@masters3d.com>> wrote: > > Hi Chris, > > > > This is great. Thanks for spending time on this! I am in favor of `case > > #unknown` to only match unknown cases. > > > > 1) Would #uknown be available to RawRepresentable structs? > > I haven’t considered this, so I’m not sure how that would work. I had > assumed that this would be an enum specific concept. > > What do you have in mind? If your raw representation is itself an enum, then > of course this would work. > > I was just curious since a RawRepresentable structs ( and OptionSet ) are > very similar to non exhaustive enums in that they would require handling > unknown cases. Currently RawRepresentable is required to use a default even > if all cases are accounted for. > > struct Directions: OptionSet { > let rawValue: UInt8 > static let up = Directions(rawValue: 1 << 0) > } > > let myDir = Directions.up > > switch myDir > { > case .up : print("matched") > default: print("default required") > }
Since an option set has 2^N possible values, not just N, we don't expect anyone to be switching over them! And it wouldn't be correct to try to do so exhaustively anyway. Jordan
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