It just seems so obvious to create-if-nil, and makes it nice to reset stuff
that should be re-created. In my case, after my NSURLSession gets invalidated,
I wanted to set the property to nil, and next time a session was needed, it
would just get created.
Sure, I can implement this myself, but ugh.
--
Rick Mann
rm...@latencyzero.com
> On Oct 20, 2017, at 17:58, Jordan Rose <jordan_r...@apple.com> wrote:
>
> It's not directly related to property behaviors. It was a bug that only
> worked with ImplicitlyUnwrappedOptional properties; we patched the type
> checker bug that led to it being allowed and didn't even notice until someone
> brought it up (SR-5172).
>
> It would be possible to introduce this as an actual language feature even
> without the full property behaviors model, but we wouldn't want to just spell
> it 'lazy'. Maybe 'lazy_resettable' or something. And even though I say this,
> it's probably unlikely that such a proposal would get through swift-evolution
> in the Swift 5 timeframe.
>
> Meanwhile, it's always possible to implement it by hand, though I can see how
> that'd be annoying if you were relying on this and previously got it with a
> single '!'.
>
> class LazyResettableTest {
> private func fooInitial() -> String { return "initial value" }
> private var fooStorage: String?
> var foo: String! {
> get {
> if fooStorage == nil { fooStorage = fooInitial() }
> return fooStorage
> }
> set {
> fooStorage = newValue
> }
> }
> }
>
> Jordan
>
>
>> On Oct 19, 2017, at 19:59, David Sweeris via swift-users
>> <swift-users@swift.org> wrote:
>>
>> I don't know. IIRC (big if), though, there was talk of adding support for
>> "property behaviors"(?). Resetting lazy vars probably would've been one of
>> them, and if so, it probably got pulled so that we wouldn't risk breaking
>> source compatibility later by adding a consistent syntax for other
>> behaviors. I think. I wish I could remember who'd brought up the idea...
>> they'd probably know straight away if that's what happened.
>>
>> - Dave Sweeris
>>
>>> On Oct 19, 2017, at 5:40 PM, Rick Mann via swift-users
>>> <swift-users@swift.org> wrote:
>>>
>>> Googling for the answer, it seemed some versions of Swift supported setting
>>> a lazy var property to nil, such that the next time it's accessed, the
>>> initializer would be run again.
>>>
>>> But I just tried this in a playground in Swift 4 and it doesn't work.
>>>
>>> It sure seems to me like it should work. What's the reasoning for the
>>> current behavior?
>>>
>>> --
>>> Rick Mann
>>> rm...@latencyzero.com
>>>
>>>
>>> _______________________________________________
>>> swift-users mailing list
>>> swift-users@swift.org
>>> https://lists.swift.org/mailman/listinfo/swift-users
>>
>> _______________________________________________
>> swift-users mailing list
>> swift-users@swift.org
>> https://lists.swift.org/mailman/listinfo/swift-users
>
_______________________________________________
swift-users mailing list
swift-users@swift.org
https://lists.swift.org/mailman/listinfo/swift-users
