[External] : Re: RFR: 8291769: Translation of switch with record patterns could be improved

[forax at univ-mlv.fr]

[...] 

>> "provide new bindings" => do you have an example of that ?

> Sure:

> public class TA {
> public static void main(String... args) {
> Object o = new Box("");
> switch (o) {
> case Box b when b.o() instanceof String s -> System.err.println(s);
> default -> {}
> }
> }
> record Box(Object o) {}
> }

> (There can be any number of new bindings from the guard, of course.)

>> I don't think a guard should be allowed to do that. It looks like a big gunfoot
>> to me.

> I believe the current specification supports guards that introduce new bindings:

> [
> http://cr.openjdk.java.net/~gbierman/jep427%2b405/jep427+405-20220601/specs/patterns-switch-record-patterns-jls.html#jls-6.3.4
> |
> http://cr.openjdk.java.net/~gbierman/jep427%2b405/jep427+405-20220601/specs/patterns-switch-record-patterns-jls.html#jls-6.3.4
> ]

> To me, it seems desirable. In any case, an implementation PR is probably not
> very well suited to discuss opinions on what should be specced. In particular
> (but not only) a PR that is not expected to change the semantics.
Ok, thanks for the example, it means we should lift the when expression not has a static method but as a static pattern method, something which will be more clear when we will have a better idea about how to do that once user defined pattern method like Optional.of(value -> ...) will be introduced. 

Rémi 
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