On Fri, Apr 22, 2016 at 11:34 PM, John McCall <rjmcc...@apple.com> wrote:
> On Apr 22, 2016, at 11:11 PM, Jacob Bandes-Storch <jtban...@gmail.com> > wrote: > On Fri, Apr 22, 2016 at 10:50 PM, John McCall <rjmcc...@apple.com> wrote: > >> >> I have not been following this discussion, but I would be extremely antsy >> about guaranteeing any particular representation for the set of values. >> Guaranteeing a contiguous array implementation seems like a really bad >> idea, especially if that's taken to mean that we're going to actually >> provide a static global array. But there's no way to avoid providing a >> public API, because a public conformance itself implies a public API with >> some level of corresponding overhead. >> > > A "compiler magic" version of the feature, like #allValues(MyEnum), could > generate a static array *internal* to the caller's module, but I'm sure > there are implications or details of this which I'm not aware of. > > > That cannot be reconciled with resilience. The caller cannot reliably > know the set of stored cases; only the defining module can. > > For similar reasons, only the defining module can be allowed to magically > derive a conformance to your protocol, if indeed it's done with a protocol. > What should/can this mean for enums imported from Obj-C, via other modules, or bridging headers / custom module maps? In these cases, the defining module has no Swift code. Is there a way to do it with pre-existing metadata in the module?
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