On Tue, Apr 26, 2016 at 5:47 PM, Tony Allevato <[email protected]> wrote:
> That seems like a purely syntactic concern that could potentially be > addressed in other ways, though. I'm not sure the choice of "duplicate all > operators using verbosely-named methods" is the best one for the reasons I > mentioned above, and the question of "how do we cleanly unify operators > with other protocol requirements?" seems out-of-scope and orthogonal to > this proposal. > > Given that we already have existing cases in the language where operators > are declared within protocols (`Equatable` being the first one that comes > to mind), I would recommend that this proposal follow that pattern for > consistency and then the community continue a separate discussion about > operators in protocols, which may or may not lead to changes across the > entire language and standard library. The protocol operators discussion > feels like a much larger topic that deserves to be discussed in its own > right without bogging down the rest of this proposal. > Agreed; clearly changes to Equatable are orthogonal to this proposal and would need to be discussed separately. However, I support the specific implementation used by the FloatingPoint protocol which is being discussed, and I prefer it to the "old-style" alternative. I suspect that the design came up as a necessity to work around compiler inefficiencies, though I still hope that a more widespread change will be forthcoming :-) Nicola > > > On Tue, Apr 26, 2016 at 8:18 AM David Sweeris <[email protected]> wrote: > >> I’m with Nicola on this one. Operators are currently odd in that they >> have to be declared globally. Everything else about protocol conformance is >> kept within the conforming type. >> >> - Dave Sweeris >> >> >> On Apr 26, 2016, at 9:28 AM, Tony Allevato via swift-evolution < >> [email protected]> wrote: >> >> On Sun, Apr 24, 2016 at 2:57 AM Nicola Salmoria via swift-evolution < >> [email protected]> wrote: >> >>> > > func isEqual(to other: Self) ->Bool >>> > > func isLess(than other: Self) ->Bool >>> > > func isLessThanOrEqual(to other: Self) ->Bool >>> > >>> > I'm still not sure why these are methods instead of operators. >>> >>> I think this is an *excellent* choice, and I hope it is the first step >>> to completely removing operators from protocols. >>> >>> IMHO throwing operators into protocols is inconsistent and confusing. >>> Having regular methods and a single generic version of the operator that >>> calls down on the type’s methods is clearer and guarantees that generic >>> code can avoid ambiguities by calling the methods directly, instead of >>> having to rely only on heavily overloaded global operators. >>> >> >> I personally disagree on this point. To me, a protocol describes a set of >> requirements for a type to fulfill, which includes things other than >> methods. Just as a protocol can define initializers, properties, and >> associated types that a type must define in order to conform, it makes >> sense that a protocol would also define which operators a conforming type >> must support. >> >> Introducing a mapping between names and operators poses a few problems: >> >> – IMO, they are overly verbose and add noise to the definition. This >> makes the language look less clean (I'm getting visions of NSDecimalNumber). >> – They expose two ways to accomplish the same thing (writing >> `x.isEqual(to: y)` and `x == y`). >> – Do certain operators automatically get mapped to method names with >> appropriate signatures across all types, or does a conforming type still >> have to provide that mapping by implementing the operators separately? If >> it's the latter, that's extra work for the author of the type writing the >> protocol. If it's the former, does it make sense to automatically push >> these operators for all types? Should any type that has an `add` method >> automatically get `+` as a synonym as well? That may not be desirable. >> >> I'm very supportive of the floating-point protocol proposal in general, >> but I feel the arithmetic and comparison operations should be exposed by >> operators alone and not by methods, where there is a suitable operator that >> has the intended meaning. >> >> >> >>> >>> — >>> Nicola >>> >>> _______________________________________________ >>> swift-evolution mailing list >>> [email protected] >>> https://lists.swift.org/mailman/listinfo/swift-evolution >>> >> _______________________________________________ >> swift-evolution mailing list >> [email protected] >> https://lists.swift.org/mailman/listinfo/swift-evolution >> >> >>
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