[swift-evolution] two protocols with the same method name

[Andrew Bennett]

Sorry if this is already mentioned, but I quite like C#'s "Explicit
Interface Implementation" approach:

https://msdn.microsoft.com/en-us/library/ms173157.aspx


Basically:

var Marriageable.ring: String? { ... }
var CallReceivable.ring: String? { ... }

to call it you could do self.ring if it was unambiguous, otherwise:

(self as Marriageable).ring
(self as CallReceivable).ring



On Mon, Jan 11, 2016 at 9:51 AM, Brent Royal-Gordon via swift-evolution <
swift-evolution at swift.org> wrote:

> > By giving warning simply for same name, it will be quite annoying when
> the project run into this situation without any wrong. For example:
> >
> > protocol ForwardIndexType : _Incrementable {
> >     @warn_unused_result
> >     public func advancedBy(n: Self.Distance) -> Self
> > }
> >
> > extension ForwardIndexType {
> >     @warn_unused_result
> >     public func advancedBy(n: Self.Distance) -> Self
> >     @warn_unused_result
> >     public func advancedBy(n: Self.Distance, limit: Self) -> Self
> >     @warn_unused_result
> >     public func distanceTo(end: Self) -> Self.Distance
> > }
> >
> > protocol BidirectionalIndexType : ForwardIndexType
> > extension BidirectionalIndexType {
> >     @warn_unused_result
> >     public func advancedBy(n: Self.Distance) -> Self
> >     @warn_unused_result
> >     public func advancedBy(n: Self.Distance, limit: Self) -> Self
> > }
>
> Firstly, for methods and subscriptors the "name" would actually encompass
> the entire signature, so `advancedBy(_:)` and `advancedBy(_:limit:)` would
> not conflict because they have different signatures.
>
> Secondly, `ForwardIndexType` and `BidirectionalIndexType` are *not*
> unrelated protocols—one of them conforms to the other. Thus, we can assume
> that `BidirectionalIndexType` knows about `ForwardIndexType`'s `advancedBy`
> methods and intends for its versions to have compatible semantics.
>
> If instead `BidirectionalIndexType` did *not* conform to
> `ForwardIndexType`, and `RandomAccessIndexType` tried to conform to both
> `ForwardIndexType` and `BidirectionalIndexType`, *then* we would get an
> error, because two independent protocols would have declared `advancedBy(_:
> Self.Distance) -> Self` methods and it's possible they meant for them to
> have different semantics.
>
> --
> Brent Royal-Gordon
> Architechies
>
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> swift-evolution mailing list
> swift-evolution at swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
>
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