Yes, but it's not very discoverable. Plus, if the subclass existentials
proposal is accepted, it would actually allow us to do:
class C {}
extension C & P1 {}
> On 22 Feb 2017, at 08:06, Jacob Bandes-Storch <[email protected]> wrote:
>
> This works today:
>
> protocol P1{}
> protocol P2{}
>
> extension P1 where Self: P2 {
> func foo() {}
> }
>
> func bar(x: P1 & P2) {
> x.foo()
> }
>
>
>> On Tue, Feb 21, 2017 at 10:53 PM, David Hart via swift-evolution
>> <[email protected]> wrote:
>> Hello list,
>>
>> Found out yesterday that you can’t extend all existentials in Swift:
>>
>> protocol P1 {}
>> extension P1 {}
>> // works as expected
>>
>> protocol P2 {}
>> extension P1 & P2 {}
>> // error: non-nominal type 'P1 & P2' cannot be extended
>>
>> extension Any {}
>> // error: non-nominal type 'Any' cannot be extended
>>
>> extension AnyObject {}
>> // error: 'AnyObject' protocol cannot be extended
>>
>> I’d like to write a proposal to lift some of those restrictions. But the
>> question is: which should be lifted? P1 & P2 seems like an obvious case. But
>> what about Any and AnyObject? Is there a design reason that we shouldn’t
>> allow it?
>>
>> David.
>>
>> _______________________________________________
>> swift-evolution mailing list
>> [email protected]
>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>
>
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