[swift-evolution] Add something like [unowned self] syntax for passing instance methods into closure parameters without creating retain cycles

[Callionica (Swift)]

Oh. That's great. Very useful. Thanks for the info.

On Thursday, September 15, 2016, Jordan Rose <jordan_rose at apple.com> wrote:

> Unowned pointers aren't dangling in debug builds; they're more like
> zombie-detection, where you get a deterministic trap if you access them
> after the original instance is strong-released for the last time. I can't
> remember if this is enabled in release builds as well; under -Ounchecked
> they do become unsafe-unretained.
>
> Jordan
>
>
> On Sep 14, 2016, at 10:51, Callionica (Swift) via swift-evolution <
> swift-evolution at swift.org
> <javascript:_e(%7B%7D,'cvml','swift-evolution at swift.org');>> wrote:
>
> How do you figure unowned pointers help you detect errors? Dangling
> pointers give you no guarantees.
>
> On Wednesday, September 14, 2016, Karl Wagner via swift-evolution <
> swift-evolution at swift.org
> <javascript:_e(%7B%7D,'cvml','swift-evolution at swift.org');>> wrote:
>
>> Sorry to hijack the thread, but I was working to fix the fact that we
>> can't have optional unowned pointers in swift and Jordan said he didn't
>> think anybody ever asked for it before. It made me worry about the kind of
>> practices swift is encouraging.
>>
>> The overhead of using weak pointers isn't massive, but it involves
>> locking and updating global tables (http://stackoverflow.com/ques
>> tions/23689155/lots-of-overhead-for-weak-property). Unowned pointers
>> don't have this overhead, and can also help you detect errors because they
>> are fail-deadly.
>>
>> But yeah, I'd like to be able to reference non-owning instance methods.
>>
>> This
>> <https://itunes.apple.com/app/apple-store/id922793622?pt=814382&mt=8&ct=how_i_email>
>> is how I Email now
>>
>>
>> On Sep 14, 2016 at 7:45 am, <Rick Mann> wrote:
>>
>>
>> > On Sep 13, 2016, at 22:34 , Xiaodi Wu via swift-evolution <swift-evolution at swift.org> wrote:
>> >
>> > It's similar to Linus' argument against using kernel debuggers (https://lwn.net/2000/0914/a/lt-debugger.php3). Understanding your code at a level above the source, and being careful, make you a better developer. There are no features in swift which compensate for a lack of understanding about how your code works.
>>
>> Get off my lawn!
>>
>>
>> --
>> Rick Mann
>> rmann at latencyzero.com
>>
>>
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