> On 4 Oct 2016, at 16:30, Tim Vermeulen via swift-evolution
> <[email protected]> wrote:
>
> I think I agree with you. The postfix `!` operator is always shorthand for
> `fatalError()` (and some more syntax), and it would fit nicely with `default:
> fatalError()`.
>
> The Swift usage of `?` is indeed different than `default: break` would do, so
> `switch?` wouldn’t convey the right message. I hadn’t given it enough
> thought. I still think a shorthand for `default: break` would be _nice_, but
> it surely shouldn’t change the `?` consistency, it also shouldn’t replace the
> current `switch` (as exhaustiveness is very useful) and it’s probably not
> worth introducing new syntax for.
>
>> On 4 Oct 2016, at 16:36, Xiaodi Wu <[email protected]
>> <mailto:[email protected]>> wrote:
>>
>> There is a plausible argument for `switch!`, because it is not possible for
>> the compiler to prove exhaustiveness in all circumstances where you might
>> know it to be the case.
>>
>> However, I'd be very against `switch?`: it undermines the exhaustiveness
>> guarantee of the switch statement and is wholly inconsistent with Swift
>> usage of `?`, which indicates the possibility of an Optional. We simply
>> don't need a new spelling for `default: break`.
I agree with Tim; I'm a +1 for switch! for a convenient means of erroring out,
but I think switch? is a bit too different from normal usage of the
question-mark.
One other alternative might be if there could be some kind of switch else
syntax, kind of like a guard statement, allowing options on what to do? Only
problem is how best to structure it, as the use of break might confusing as to
its scope, like so:
switch(foo) else break { // Break from the switch, or the enclosing
block?
So I'm not 100% on that. But it would mean that switch! would be a shorthand
for switch else fatalError()._______________________________________________
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