Hello! On Mon, May 30, 2022 at 6:54 PM Brian Goetz <brian.go...@oracle.com> wrote: > I must admit to being very surprised that you can do this at all! I > don't recall discussion on this, and had you asked me, I would have said > that `final` has no place in type-test patterns. Yet, I just tried it > with jshell and it does work as you say. I am surprised. > > Can someone recall any discussion over this? (Surely now someone will > point me to where I agreed to this.) > > Worse, it even works in switch labels! This is definitely not what I > had in mind. Did this happen because we reused the local variable > production for type patterns? Since switch patterns are about to exit > preview, I think we need to fix this ASAP, before switch exits preview.
Erm... I actually thought that it was your idea to allow the 'final' modifier on patterns. This change was introduced in Java 16 (when patterns for instanceof were finalized). Here's the initial e-mail from you (item 2): https://mail.openjdk.java.net/pipermail/amber-spec-experts/2020-August/002433.html There was also subsequent discussion but eventually nobody was really against and this was finalized. > > > It looks like, > > "obj instanceof final Point(int x, int y) p" syntax is not allowed > > which brings some asymmetry > > - In the first case I can use LOCAL_VARIABLE annotations like 'obj > > This very question is why I would not have encouraged us to try to do > this for type test patterns at all! > > > instanceof @Cartesian Point p'. It looks like I cannot do the same in > > the second case, which is another asymmetry. > > We definitely intended to not allow declaration annotations. But they are allowed for type test patterns, since Java 16. > As to > type-use annotations; well, that's a different problem, and I'm not > quite sure what to do. For sure, we are not going to amend the > XxxTypeAnnotations attributes to reify the position of these > annotations. If we allow them and make them available only to > annotations processors only, that's another kind of asymmetry, that > someone else will complain about. > > > So if I want to upgrade the type test pattern on a record type to a > > record pattern to match components, I need to give up some features > > like finality and annotations. Is this intended? > > It was not really intended that you got those features in the first place. > >
