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

[肇鑫]

I don't think self.Marriageable.ring is a good idea. As self.Type
conforms Marriageable protocol, and a protocol is not a property of a
class/struct/enum.

Let's go back with the definition of the Protocol.

A protocol defines a blueprint of methods, properties, and other
>> requirements that suit a particular task or piece of functionality. The
>> protocol can then be adopted by a class, structure, or enumeration to
>> provide an actual implementation of those requirements. Any type that
>> satisfies the requirements of a protocol is said to conform to that
>> protocol.
>
>
>> In addition to specifying requirements that conforming types must
>> implement, you can extend a protocol to implement some of these
>> requirements or to implement additional functionality that conforming types
>> can take advantage of.
>
>
>>
So if there are some independent protocols accidentally sharing the same
vars or functions, this does not violate the definition of the protocol.
Should the compiler warns the programmer? Maybe, as we can not sure there
must be conflicts. So I think the alert level is between warning and
silence.

Let's also see the solutions. The solutions in other languages inspire us
what to do. One is to change the properties names, the other is to cast the
type to the protocol.

I think the prior method is much easier to go with. As currently,  you
can't name a store properties in extension, and you can't have two
properties with the same name in extension. However, there is also a
problem after you rename the property. As it is no longer the name that
defined in the protocol, you can use it with (self as Protocol).name. So
maybe we can use lable to solve the problem.

Basically:
           type A: Marriageable, CallReceivable {

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

to call it :

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


zhaoxin


On Mon, Jan 11, 2016 at 8:17 AM, Wallacy via swift-evolution <
swift-evolution at swift.org> wrote:

> I Like this C#'s "Explicit Interface Implementation".
> The cast to call is understandable, it's good, but just think about. If we
> use "self.Marriageable.ring" or "variable.Marriageable.ring" will make more
> symmetrical with the implementation? "dot protocol" can be used to all
> "explicit call", ambiguous or not.
>
> Em dom, 10 de jan de 2016 às 21:49, Andrew Bennett via swift-evolution <
> swift-evolution at swift.org> escreveu:
>
>> 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
>>>
>>> _______________________________________________
>>> swift-evolution mailing list
>>> swift-evolution at swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-evolution
>>>
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>>
>
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>


-- 

Owen Zhao
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