On Tue, Jan 9, 2018 at 10:10 PM, Chris Lattner <clatt...@nondot.org> wrote:
> On Jan 9, 2018, at 3:07 PM, Jose Cheyo Jimenez <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")
}
> > 2) How is the #uknown pattern accomplished? Are you suggesting to
> capture all the compile time known cases so you can do a diff during
> > runtime? (Sorry this is not obvious to me)
>
> The internals of the compiler would handle this, it is difficult to
> explain unless you know the bowels of silgen and irgen :-)
>
> -Chris
>
>
>
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