Sent from my iPhone
> On Feb 1, 2017, at 8:46 PM, Slava Pestov <[email protected]> wrote: > > >>> On Feb 1, 2017, at 4:09 PM, Douglas Gregor via swift-evolution >>> <[email protected]> wrote: >>> >>> >>> On Feb 1, 2017, at 3:13 PM, David Hart <[email protected]> wrote: >>> >>> Second question inline: >>> >>> >>> >>> Sent from my iPhone >>> On 1 Feb 2017, at 23:09, David Hart <[email protected]> wrote: >>> >>>> I did consider it, but didn’t want to put too much on your plate for Swift >>>> 4. But if you’re mentioning it, I’ll go ahead and add it to the second >>>> version of the proposal. >>>> >>>> By the way, what you is your point of view about the discussions we’ve had >>>> concerning the positioning of the class constraint? >>>> >>>> David. >>>> >>>>>> On 1 Feb 2017, at 22:58, Douglas Gregor <[email protected]> wrote: >>>>>> >>>>>> >>>>>> On Jan 29, 2017, at 8:39 AM, David Hart <[email protected]> wrote: >>>>>> >>>>>> Hello, >>>>>> >>>>>> As promised, I wrote the first draft of a proposal to add class >>>>>> requirements to the existential syntax. Please let me know what you >>>>>> think. >>>>>> >>>>>> https://github.com/hartbit/swift-evolution/blob/subclass-existentials/proposals/XXXX-subclass-existentials.md >>>>> >>>>> This looks good! I’m looking forward to the second draft, but I have one >>>>> question. >>>>> >>>>> Did you consider the generalized “class” constraint? IIRC, this was in >>>>> Austin’s larger proposal, and it allowed for (e.g.) >>>>> >>>>> typealias CustomStringConvertibleClass = class & >>>>> CustomStringConvertible // class that conforms to >>>>> CustomStringConvertible >>>>> >>>>> and potentially a wonderful cleanup where AnyObject ceases to be a weird >>>>> special protocol and instead becomes >>>>> >>>>> typealias AnyObject = Any & class >>>>> >>> >>> Austin's proposal defines it as: >>> >>> typealias AnyObject = class >>> >>> Is Any necessary? >> >> Nah, it should be okay to just have “class” there. > > This would mean ‘class’ can appear anywhere we expect to parse a type, or > would we have a special grammar rule for the RHS of a typealias? This is sorta why I'm nervous about it and suggested the "Any & class" thing. In theory any type can in an expression, so class.self Would be a valid expression. I don't think it's actually ambiguous, but it feels... odd. And can mess with parser recovery. - Doug > Slava > >> >> - Doug >> >> _______________________________________________ >> swift-evolution mailing list >> [email protected] >> https://lists.swift.org/mailman/listinfo/swift-evolution >
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