On 3 Nov 2016, at 8:37 PM, Erica Sadun via swift-users <swift-users@swift.org
<mailto:swift-users@swift.org>> wrote:
> private enum StringEnum: String { case one, two, three }
> public init(strings: [String]) {
> var set = MyOptionSet()
> strings.flatMap({ StringEnum(rawValue: $0) })
> .flatMap({ MyOptionSet(rawValue: 1 << $0.hashValue) })
> .forEach { set.insert($0) }
> _rawValue = set.rawValue
> }
I’m curious about relying on the hash value of an enum case being its
declaration-order index. A sage
(http://ericasadun.com/2015/07/12/swift-enumerations-or-how-to-annoy-tom/
<http://ericasadun.com/2015/07/12/swift-enumerations-or-how-to-annoy-tom/>)
warns that this is an implementation detail. I haven’t seen anything saying it
is API. Has it been resolved?
It’s the most plausible implementation, but I’d think code that relies on case
order would break silently (likely at widely-separated locations) if a case
were inserted or removed. That suggests to me it’s not possible to regularize
this behavior.
Folkloric API (like SEL ↔︎ char* in ObjC) makes me itch.
— F
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