[swift-corelibs-dev] [swift-evolution] Proposal: Conforming NSDate to Comparable

Stephen Celis stephen.celis at gmail.com
Sun Dec 6 11:48:21 CST 2015

Seems to me that anything with `-compare:` could conform to Comparable. The list, however, is surprisingly short, and half bridge over to native Swift types that are already Comparable:

- [NSDate compare:]
- [NSIndexPath compare:]
- [NSNumber compare:]
- [NSString compare:]

Looks like NSIndexPath may be the only other contender.


> On Dec 6, 2015, at 11:47 AM, Tony Parker via swift-evolution <swift-evolution at swift.org> wrote:
> Hi Chris,
> Thanks for bringing this idea to the list.
> Is NSDate really the only thing that we want to conform to comparable, or is there a set of classes which should do so? I’d like to think about the larger set of consequences here (and if possible, deal with one coherent answer for all of Foundation rather than do these classes one at a time).
> - Tony
>> On Dec 5, 2015, at 3:36 PM, Chris Amanse via swift-corelibs-dev <swift-corelibs-dev at swift.org <mailto:swift-corelibs-dev at swift.org>> wrote:
>> Hello Swift Developers,
>> I think it's a good idea to conform NSDate to the Comparable protocol, so instead of using:
>> if someDate.compare(today) == .OrderedAscending { }
>> Developers can easily compare using compare dates using comparison operators:
>> if someDate < today { }
>> In my opinion, the code is still readable if developers use comparison operators on NSDates.
>> Here's a quick implementation from my swift-corelibs-foundation fork: https://github.com/chrisamanse/swift-corelibs-foundation/commit/3c4eff643c5271de5bec2461798051347be13916 <https://github.com/chrisamanse/swift-corelibs-foundation/commit/3c4eff643c5271de5bec2461798051347be13916>
>> Thank you.
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