It just occurs to me that you can't put none<T> in a [T], so on optional
subscript would only be get and we would need the current subscript beside
anyway.
I have no particular opinion on the main subject, I wonder what the order of
magnitude would be that optimisation.
Pierre
> Le 20 janv. 2017 à 07:41, Russ Bishop via swift-evolution
> <swift-evolution@swift.org> a écrit :
>
>
>> On Jan 19, 2017, at 4:17 PM, Xiaodi Wu via swift-evolution
>> <swift-evolution@swift.org> wrote:
>>
>> For those times when you _don't_ know how many elements there are, don't
>> care, and for some reason can't be bothered to get `array.count`, but you
>> need to explicitly access an element by its index *and* have a useful
>> fallback value, IMO it's reasonable to have an alternative subscript like
>> the proposed `array[lenient: 10]`. But with facilities like `for...in`,
>> `map`, etc., and others like `count` and `enumerated`, it's hard to argue
>> that it's nearly as common a scenario as those where you are given a
>> known-good index.
>>
>
> I’m not sure why people keep asking for this; the extension is trivial so
> anyone who wants it can have it:
>
> extension Collection
> {
> subscript(ifExists index: Index) -> Iterator.Element? {
> guard index < self.endIndex else { return nil }
> return self[index]
> }
> }
>
> // won't assert!
> myArray[ifExists: 42]
>
>
>
> Russ
>
> _______________________________________________
> swift-evolution mailing list
> swift-evolution@swift.org
> https://lists.swift.org/mailman/listinfo/swift-evolution
_______________________________________________
swift-evolution mailing list
swift-evolution@swift.org
https://lists.swift.org/mailman/listinfo/swift-evolution
