> On May 12, 2016, at 18:34, Andrew Trick <atr...@apple.com> wrote:
>
>> - On the flip side, I think we do need to preserve the ability to
>> reference-cast in order to send Objective-C messages, at least for now. I
>> don’t know how I want to expose that to users, though. (In general it’s
>> probably worth seeing how unsafeBitCast is used in the wild and what we’d
>> recommend instead.)
>
> Does ``X as Y`` fail for some reason? We have unchecked versions of ``X as
> Y`` for performance reasons: ``unsafeDowncast`` and ``_unsafeReferenceCast``.
The particular case I’m thinking about is where we reinterpret an AnyObject as
an @objc protocol because we don’t know the dynamic type we would need to add a
method to. This doesn’t happen much, and maybe we just say sending arbitrary
messages requires an ObjC-side workaround. Or we commit to
‘_unsafeReferenceCast’ and de-underscore it.
(_unsafeReferenceCast is probably a better choice for StdlibUnittest, which is
where I used this.)
Jordan
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