Re: [swift-evolution] Self behaves inconsistently in protocol method signatures

> On Dec 28, 2015, at 12:43 PM, Joe Groff wrote: > >> >> On Dec 28, 2015, at 10:31 AM, Matthew Johnson > > wrote: >> >>> >>> On Dec 28, 2015, at 12:02 PM, Joe Groff >> > wrote: >>> On Dec 28, 2015, at 8:49 AM, Matthew Johnson

Re: [swift-evolution] Self behaves inconsistently in protocol method signatures

> On Dec 28, 2015, at 10:31 AM, Matthew Johnson wrote: > >> >> On Dec 28, 2015, at 12:02 PM, Joe Groff > > wrote: >> >>> >>> On Dec 28, 2015, at 8:49 AM, Matthew Johnson via swift-evolution >>> mailto:swift-evolution@swift.org>> wrote: >>> >>> I have brought up the

Re: [swift-evolution] Self behaves inconsistently in protocol method signatures

> On Dec 28, 2015, at 12:02 PM, Joe Groff wrote: > >> >> On Dec 28, 2015, at 8:49 AM, Matthew Johnson via swift-evolution >> wrote: >> >> I have brought up the idea of a non-covarying Self a few times. >> >> I was surprised to realize that Self is actually non-covarying when used for >>

Re: [swift-evolution] Self behaves inconsistently in protocol method signatures

> On Dec 28, 2015, at 12:04 PM, Developer wrote: > > That doesn't look like a variance issue to me, that's about the same > "information" invariant I talked about before. The former works because self > resolves to an invariant type, the type of the implementing structure, which > satisfies

Re: [swift-evolution] Self behaves inconsistently in protocol method signatures

That doesn't look like a variance issue to me, that's about the same "information" invariant I talked about before. The former works because self resolves to an invariant type, the type of the implementing structure, which satisfies the requirement Self introduces. The latter does not because

Re: [swift-evolution] Self behaves inconsistently in protocol method signatures

> On Dec 28, 2015, at 8:49 AM, Matthew Johnson via swift-evolution > wrote: > > I have brought up the idea of a non-covarying Self a few times. > > I was surprised to realize that Self is actually non-covarying when used for > parameters in protocol declarations! > > Here is an example dem

Re: [swift-evolution] Self behaves inconsistently in protocol method signatures

> On Dec 28, 2015, at 11:19 AM, Developer wrote: > > My understanding of Self is that it is a special generic parameter resolved > by the type system to the type of the implementing structure. That > resolution must be invariant because the implementing structure (here, > non-final classes)

Re: [swift-evolution] Self behaves inconsistently in protocol method signatures

My understanding of Self is that it is a special generic parameter resolved by the type system to the type of the implementing structure. That resolution must be invariant because the implementing structure (here, non-final classes) can choose to yank the protocol's invariants out from under yo

[swift-evolution] Self behaves inconsistently in protocol method signatures

I have brought up the idea of a non-covarying Self a few times. I was surprised to realize that Self is actually non-covarying when used for parameters in protocol declarations! Here is an example demonstrating this: protocol P { func foo(s: Self) } protocol Q { func bar() -> Self }