One thing I really like that Erica mentioned in the earlier discussion is the
case of guard unwrapping [weak self] in closures. I've taken to creating an
alternate self (guard let ss = self else { return }) constant and using that.
But it always felt inelegant. The proposed case works without falling prey to
the protection against redefining self that the compiler still needs to enforce
and does it in a way that's clear and concise.
Sent from my iPhone
> On Oct 31, 2016, at 6:46 PM, William Sumner via swift-evolution
> <swift-evolution@swift.org> wrote:
>
>
>> On Oct 31, 2016, at 3:44 PM, Erica Sadun via swift-evolution
>> <swift-evolution@swift.org> wrote:
>>
>>
>>> On Oct 31, 2016, at 1:51 PM, Xiaodi Wu via swift-evolution
>>> <swift-evolution@swift.org> wrote:
>>>
>>> An alternative that would seem to satisfy some objections is to have a
>>> distinct "unwrap" statement--as in: "unwrap x else { ... }".
>>
>> I'd be against this alternative as it is doing the work of a guard statement
>> (including the "must exit scope" rule) with a new keyword and unneeded
>> redundancy.
>>
>> Adding "unwrap" is local. It performs one very common task with added safety
>> (avoids unintended shadow effects) and introduces succinctness and clarity.
>> In other words, it is a highly focused changed with a measurable benefit in
>> use.
>>
>> Compare:
>>
>> * "Introduce the unwrap statement that acts like guard but is limited to
>> optionals" creates unnecessary language verbosity.
>>
>> * "guard x else ", meaning "treat optional values differently than all other
>> items in a conditional list", fails because it obscures rather than adds
>> intent. Worse, it would lead to issues with Boolean optionals whose wrapped
>> value is later used within the same condition.
>>
>> Xiaodi, you mentioned an alternative approach and I'd love a peek at what
>> that is.
>>
>> — Erica
>
> Your proposed form of unwrap naturally works in multiple places with clear
> readability:
>
> var foo: Any?
> if unwrap foo {}
>
> while unwrap foo {}
>
> guard unwrap foo else { return }
>
> Preston
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