> De: "Brian Goetz" <brian.go...@oracle.com> > À: "Remi Forax" <fo...@univ-mlv.fr>, "John Rose" <john.r.r...@oracle.com> > Cc: "amber-spec-experts" <amber-spec-experts@openjdk.java.net> > Envoyé: Vendredi 23 Avril 2021 22:38:41 > Objet: Re: [External] : Re: Switch labels (null again), some tweaking
> On 4/23/2021 4:25 PM, Remi Forax wrote: >>> Bottom line: Trust the users to choose how >>> explicit to be with nulls. More importantly, >>> trust them with compositional notations. >> That's a solution, we do nothing and trust users. >> The other solution is to force users to explicit say that the pattern is >> total, >> by example by asking to use 'var o' instead of 'Object o', >> but we already discuss that and only me and Tagir were agreeing that it is a >> good idea. > Yes, this is what I meant by "move the distinction around." We could say that > `var x` and `Object x` are different patterns; this is a sharp edge in one > place (blows up the notion that `var` is just type inference.) We could say > that `default` and `Object x` are different patterns (which is what I'm > suggesting), which puts the sharp edge somewhere else -- it means that > people's > notion of totality is polluted by historical chance. We could have different > patterns for Object! and Object?, which is appealing in a "say what you mean" > way, but which forces users to think about a corner case all the time. For the record, I was proposing to disallow `Object o` as a total pattern (as we disallow instanceof Object o) instead of making `var x` and `Object x` two different patterns, well, it also can be seen as two different patterns with `Object o` being an invalid one. > Reasonable people can differ about which of these (or other) approach is best > for Java, but it is not reasonable to believe that we can hide this > distinction. Yes ! Rémi
