[swift-evolution] [Proposal] More lenient subscript methods over Collections (was: [Proposal] Safer half-open range operator)
Luis Henrique B. Sousa
lshsousa at gmail.com
Thu Apr 28 07:11:54 CDT 2016
As we have discussed throughout this thread, the initial proposal was
modified to include alternative subscript methods instead of modifying the
default operator/subscript behaviour.
The first draft is here:
I've also put this as a gist so that you can leave comments with respect to
the proposal document itself. Any suggestion or help is very welcome.
On Mon, Apr 11, 2016 at 1:23 PM, Luis Henrique B. Sousa <lshsousa at gmail.com>
> This proposal seeks to provide a safer ..< (aka half-open range operator)
> in order to avoid **Array index out of range** errors in execution time.
> Here is my first draft for this proposal:
> In short, doing that in Swift causes a runtime error:
> let a = [1,2,3]
> let b = a[0..<5]
> > Error running code:
> > fatal error: Array index out of range
> The proposed solution is to slice the array returning all elements that
> are below the half-open operator, even though the number of elements is
> lesser than the ending of the half-open operator. So the example above
> would return [1,2,3].
> We can see this very behaviour in other languages, such as Python and Ruby
> as shown in the proposal draft.
> This would eliminate the need for verifications on the array size before
> slicing it -- and consequently runtime errors in cases when the programmer
> Viewing that it is my very first proposal, any feedback will be helpful.
> Luis Henrique Borges
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