On 06.06.2016 21:02, Rob Norback wrote:
First of all, thank you all for bringing me up to date so quickly. I
looked over the proposal and it looks awesome.
But as Chris mentioned, this doesn't solve the expected behavior and
ambiguity of ```Array<Int?>```
In this case I would expect the default behavior (myArray[4]) without using
myArray[checking: 4] should return a nil in this case.
As Luis already noted, there was a discussion started with exactly the same
suggestion : return optional for wrong index/range. During the discussion
consensus was(I believe so) found that such proposal could not be
supported. But, as an alternative, special explicit syntax for
optional/checking results for index/range parameter was suggested. I'd
recommend to read messages of these discussions.
As for [Int?], I believe we need no any additional solution for this
special case: you have to check if index is in array's bounds and if it is,
get value using standard subscript method.
And Chris, I think it would make the most sense to have myArray[0] = nil to
be stored if the index is in Range, and for myArray[100] = nil to give a
warning of no assignment being made because index is out of range, kind of
like an unused variable. Right now myArray[100] = nil gives you
EXC_BAD_INSTRUCTION. Then if you assigned myArray[100] = 200, that would
have to simply change the Range.
Chris, I honestly have to think more about that ambiguity with dictionaries.
I can see that this would definitely need some further fleshing out, but it
seems to be sufficiently different from Luis' proposal to perhaps merit
it's own proposal.
It's up to you Luis, but I think this might be a bit more controversial
then the changes you've proposed, making it possible for your proposal
getting rejected. (I want your proposal accepted, since I would use those
features today). Partial acceptance of a proposal doesn't seem to be a
thing. (Once again please correct me if I'm wrong).
On Mon, Jun 6, 2016 at 11:46 AM Luis Henrique B. Sousa <lshso...@gmail.com
<mailto:lshso...@gmail.com>> wrote:
Thanks Vladimir,
The correct link is this one (with the additional min/max operations in
the implementation):
https://github.com/luish/swift-evolution/blob/proposal-lenient-collection-subscripts/proposals/nnnn-more-lenient-collections-subscripts.md
Here is the pull request on the swift-evolution
repo: https://github.com/apple/swift-evolution/pull/328
Any help or suggestion to improve the proposal is welcome. :-)
- Luis
On Mon, Jun 6, 2016 at 6:10 PM, Vladimir.S via swift-evolution
<swift-evolution@swift.org <mailto:swift-evolution@swift.org>> wrote:
Please find this draft of proposal(hope this is correct link for
latest version):
https://github.com/luish/swift-evolution/blob/more-lenient-subscripts/proposals/nnnn-more-lenient-collections-subscripts.md
The main idea is to introduce 2 new subscript methods: [clamping:]
and [checking:]
There was discussion in "[Proposal] More lenient subscript methods
over Collections" and (older) "[Proposal] Safer half-open range
operator"
On 06.06.2016 19:50, Rob Norback via swift-evolution wrote:
Hi Everyone!
This is my first time emailing the swift evolution list, so if
this topic
has already been discussed please let me know. I looked
through all the
accepted and rejected proposals and it doesn't seem to be on there.
The main thought is that dictionaries return optionals, so why
not arrays?
Or other CollectionTypes for that matter. I would think this
would be the
expected behavior in this situation:
var myArray:[String?] = []
print(myArray[4])
// EXC_BAD_INSTRUCTION, but could just be Optional(nil)
Then you could do things like
if let arrayValue = myArray[4] {
// do something
}
Of course you could simply check with with the count, but
considering
Swift's use of optionals to represent empty variables rather
than erroring
out or returning an empty String, I think this functionality
would be
appropriate to include in the Swift standard library.
And there's about 15,000 people who've looked for this
functionality in the
last year:
http://stackoverflow.com/questions/25329186/safe-bounds-checked-array-lookup-in-swift-through-optional-bindings.
Please let me know what you think.
Best,
Rob Norback
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