Fw: JEP 455: Non-enhanced switch statements

[Maurizio Cimadamore]

Sure - but this logic is only applied to switch expression featuring 
enums AFAIK - switch statements with enums are non-exhaustive (and I 
think that will have to stay that way).

Maurizio

On 27/10/2023 15:28, Brian Goetz wrote:
>
>>
>> Unfortunately enum is that one case where compatibility dictates that 
>> we can't be exhaustive, which is a little sad... but I think that's 
>> the best we can do?
>>
>
> What we do for enums is do exhaustiveness checking based on the 
> compile-time state of the world, and generate a synthetic default 
> clause that deals with separately-compiled changes.  (Same with sealed 
> types.)  This works pretty well, as it lets us type-check a (new) 
> switch like
>
>     int wavelengthNm = switch (trafficLightColor) {
>         case RED -> 700;
>         case YELLOW -> 580;
>         case GREEN -> 540;
>     }
>
> and not require a "silly" default, while offering runtime protection 
> against novel colors showing up at runtime, and notifying the user at 
> a subsequent compile if something unexpectedly changed.