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. 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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