[patterns-instanceof] Spec for next version of Patterns in instanceof JEP
gavin.bierman at oracle.com
Mon Oct 12 19:55:40 UTC 2020
Following the announcement of JEP 394  the latest version of the spec is now available at:
I have fixed the bugs spotted by Brian in the previous draft. I have also tidied up the treatment of annotations (See sections 188.8.131.52 and 9.7.4 along with the refactored grammar for type test patterns 184.108.40.206)
Still time to pass on comments!
> On 5 Oct 2020, at 13:53, Gavin Bierman <gavin.bierman at oracle.com> wrote:
> Dear all:
> A draft of the spec for the Patterns in instanceof feature that we plan to
> finalize in JDK 16 is now available:
> [NB: The URL will change once we have a JEP number, and will be announced.]
> The changes are the same as those in the second preview that was released in
> Java SE 16, except for minor editorial changes and the following:
> - To lift the restriction that pattern variables are implicitly final. This
> allows pattern variables to be considered as a strict subset of local
> variables. A number of simplifications to the spec result from this change.
> - To make it a compile-time error for an expression of type _S_ to be matched
> against a pattern of type _T_, where _S_ is a subtype of _T_. (This pattern
> match will always succeed and is then pointless. The opposite case, where a
> pattern match will always fail is already a compile-time error.)
> Comments welcome!
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