[swift-evolution] [Proposal] Safer half-open range operator
Luis Henrique B. Sousa
lshsousa at gmail.com
Wed Apr 13 09:53:55 CDT 2016
Many thanks @Pyry, it's great to see those changes coming in swift 3. The
examples using *clamp* you mentioned here would do what I'm proposing, but
I totally agree with @Vladimir that we could have a more clear and
*swift-ly* way to concisely wrap those operations.
The behaviour pointed out by him looks very nice and doable to me.
a = [1,2,3]
a[-1..<6] - raises runtime error (right behavior by default, doesn't affect
a[truncate: -1..<6] - produces [1,2,3] (the very behaviour I proposed
a[safe: -1..<6] - produces nil (i.e [T]?) (no runtime errors and makes it
easy to handle unexpected results)
I'd like to hear more opinions before I update my proposal with those new
subscript methods (instead of a different operator, or added as an
On Wed, Apr 13, 2016 at 2:11 PM, Vladimir.S via swift-evolution <
swift-evolution at swift.org> wrote:
> Is it really great to have a[a.indices.clamped(to: 0 ..< 5)]
> instead of a clear a[truncate: 0 ..< 5] ?
> and if it is not "a" but "arrayOfSomeValues" we have
> arrayOfSomeValues[arrayOfSomeValues.indices.clamped(to: 0 ..< 5)]
> Don't feel this is nice.
> Is it really so wrong to have additional(to "direct" functions like
> "indices.clamped" ) handy and nice-looking methods/subscripts in language?
> IMO we all want to have great language. It should be great to code in such
> language. Is it great and enjoyable to have strange long construction
> instead of handy,clear and explicit expression?
> Why don't improve the language in all possible area where we can improve
> it? I believe we should improve.
> On 13.04.2016 14:09, Pyry Jahkola via swift-evolution wrote:
>> On 11 Apr 2016, at 15:23, Luis Henrique B. Sousa via swift-evolution
>>> <swift-evolution at swift.org <mailto:swift-evolution at swift.org>> wrote:
>>> leta =[1,2,3]
>>> letb =a[0..<5]
>>> In the swift-3-indexing-model branch
>> you can /clamp/ a range just like you could clamp intervals in Swift 2. So
>> the following will work in the way you preferred:
>> let b = a[a.indices.clamped(to: 0 ..< 5)]
>> It was suggested to extend `Collection` with a subscript like `a[safe: 0
>> ..< 5]` which resembles the current subsequence subscript
>> we could bring collections even closer to ranges by extending them with
>> equivalent `.clamped(to:)` method:
>> let b = a.clamped(to: 0 ..< 5) // "safe" subsequence
>> — Pyry
>> swift-evolution mailing list
>> swift-evolution at swift.org
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