Call for feedback -- enhanced switch

[forax at univ-mlv.fr]

----- Mail original -----
> De: "Jorn Vernee" <jbvernee at xs4all.nl>
> À: "Remi Forax" <forax at univ-mlv.fr>
> Cc: "Brian Goetz" <brian.goetz at oracle.com>, "amber-dev" <amber-dev at openjdk.java.net>
> Envoyé: Dimanche 24 Mars 2019 18:55:48
> Objet: Re: Call for feedback -- enhanced switch

> Actually, I just realized that there is no `// automatic exception`
> because this is not an expression switch :) If I remove the println to
> make it compile I get:
> 
> ```
>       24: lookupswitch  { // 2
>                      1: 52
>                      2: 58
>                default: 61
>           }
>       52: iload_1
>       53: istore        4
>       55: goto          61
>       58: iload_2
>       59: istore        4
>       61: return
> ```
> (i.e. no exception)
> 
> I guess this further proves my point that existence of automatic default
> can be confusing...

hum, this one still doesn't work !

enum MyEnum {
    X, Y;
     
    public static void main(String[] args) {
         MyEnum myEnum = MyEnum.X;
         int o;
         var f = switch(myEnum) {
             case X -> o = 5;
             case Y -> o = 10;
             // automatic exception
         };
         System.out.println(o);
     }
}

> 
> Jorn

Rémi

> 
> Remi Forax schreef op 2019-03-24 18:49:
>> ----- Mail original -----
>>> De: "Jorn Vernee" <jbvernee at xs4all.nl>
>>> À: "Brian Goetz" <brian.goetz at oracle.com>
>>> Cc: "amber-dev" <amber-dev at openjdk.java.net>
>>> Envoyé: Dimanche 24 Mars 2019 17:17:28
>>> Objet: Re: Call for feedback -- enhanced switch
>> 
>>> Hi,
>>> 
>> 
>> [...]
>> 
>>> * Also, maybe a bug:
>>>     ```
>>>     enum MyEnum {
>>>         X, Y;
>>>     }
>>>     public static void main(String[] args) throws Throwable {
>>>         int x = 5;
>>>         int y = 10;
>>>         MyEnum myEnum = MyEnum.X;
>>>         int o;
>>>         switch(myEnum) {
>>>             case X -> o = x;
>>>             case Y -> o = y;
>>>             // automatic exception
>>>         };
>>>         System.out.println(o);
>>>     }
>>>     ```
>>>   Even though the switch should be exhaustive, javac complains that
>>> 'o'
>>> might not have been initialized.
>> 
>> yes, it's a bug. And ecj has the same issue :(
>> 
>>> 
>>> Cheers,
>>> Jorn
>> 
>> regards,
>> Rémi
>> 
>>> 
>>> Brian Goetz schreef op 2019-03-01 22:55:
>>>> We would like to promote enhanced switch to a permanent feature in
>>>> Java 13.  So far, the only change we are anticipating is:
>>>> 
>>>>     - change “break value” to “break-with value”.
>>>> 
>>>> This is the time for people to try it out on their codebases (there’s
>>>> even refactoring support in IDEA!) and provide feedback on what
>>>> works,
> >> > what doesn’t, and what was surprising.