> On Sep 2, 2016, at 17:50, Douglas Gregor <[email protected]
> <mailto:[email protected]>> wrote:
>
> Hello Swift community,
>
> The review of SE-0140 "Bridge Optional As Its Payload Or NSNull" begins now
> and runs through September 8, 2016. The proposal is available here:
>
> https://github.com/apple/swift-evolution/blob/master/proposals/0140-bridge-optional-to-nsnull.md
>
> <https://github.com/apple/swift-evolution/blob/master/proposals/0140-bridge-optional-to-nsnull.md>
> • What is your evaluation of the proposal?
It seems like this would improve the utility of bridging collection types (and
plist types in general), and I like that it does something more sensible than
before with the disparate bridging behavior of Optional<>. But I do have a
couple of questions:
Will specifying a nullable type parameter to collections now become legal in
Objective-C? E.g.:
- (void)takeOptionalCollection:(NSArray<id _Nullable> * _Nullable)collection;
// Bridge to [Any?]?
If not, is there any way to annotate “I want to be able to use (or not use)
NSNull in this collection”? If there is, does doing so affect any behaviors on
the Objective-C side? If there isn’t, wouldn’t it make more sense to treat
passing an optional to Any as requiring forced unwrapping (including the
implied runtime crash behavior), as is the case with other uses of optionals
now? I can’t think offhand of any use case where I would want an object, even
in pure Swift, where I didn’t know whether it was an optional or not, outside
of debugging.
Depending on the answers to these questions, I’m tentatively in favor of this
proposal.
> • Is the problem being addressed significant enough to warrant a change
> to Swift?
Honestly, I don’t feel like it is, but my opinion may not be all that valid,
since I’ve spent a great deal more time in pure Swift (and interop with pure C)
than in interop with Objective-C.
> • Does this proposal fit well with the feel and direction of Swift?
Yes, *IF* the semantics of Optional remain consistent, which I’m not yet
entirely clear on.
> • If you have used other languages or libraries with a similar feature,
> how do you feel that this proposal compares to those?
I haven’t worked with ObjC bridges in other languages.
> • How much effort did you put into your review? A glance, a quick
> reading, or an in-depth study?
A quick reading. I was not part of any previous discussion on this topic.
-- Gwynne Raskind
More magic than a mere signature can contain
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