on Tue Feb 07 2017, Guillaume Lessard <swift-users-AT-swift.org> wrote:
>> On 7 févr. 2017, at 21:57, Slava Pestov <spes...@apple.com> wrote:
>>
>>>
>>> On Feb 7, 2017, at 8:14 PM, Guillaume Lessard via swift-users
>>> <swift-users@swift.org> wrote:
>>>
>
>>> I keep running into weird things with Swift 3 Collections.
>>>
>>> A) Collection has its count property defined as an Int via IndexDistance:
>>>
>>> public protocol Collection : Indexable, Sequence {
>>> associatedtype IndexDistance : SignedInteger = Int // line 182 in
>>> Collection.swift
>>> public var count: IndexDistance { get } // line 776
>>> }
>>
>> This declaration specifies that the *default* associated type is
>> Int, not that it’s *always* Int. A Collection implementation is free
>> to use a different type as its IndexDistance if it wants.
>
> I see how I’d misunderstood that line.
>
> This being said, does this particular freedom really bring anything to
> the table? It is simply a counter (“the number of steps between a pair
> of indices”). On one hand, a “collection" that has in excess of
> Int.max/2 elements likely needs a different protocol; on the other,
> using a shorter type for a counter seems retro.
There are still plenty of 32-bit platforms that address 64-bit files,
which should be able to be modeled as Collections.
--
-Dave
_______________________________________________
swift-users mailing list
swift-users@swift.org
https://lists.swift.org/mailman/listinfo/swift-users
