> On 5 Oct 2020, at 16:20, Brian Goetz <brian.go...@oracle.com> wrote:
>
> 5.5. I think of `instanceof` as having two forms:
>
> o instanceof Type
> o instanceof Pattern
>
> This phrasing ("converted to the type indicated by the second operand") is
> consistent with the first, but I think needs a few more words to be
> consistent with the second? Every pattern has a "principal type" (making up
> a term); the principal type of a type pattern `T t` is `T`; the principal
> type of a deconstruction pattern `D(...)` is `D`. (The definition for other
> kinds of patterns like constant patterns or declared patterns are
> straightforward enough to define as needed.)
[The spec also thinks there are two forms of instanceof - see second line of
15.20.2!]
You don’t need to make up a term; it’s there already. In 14.30.1.1.:
The type of a type test pattern is the ReferenceType.
I use this notion of “type of a pattern” elsewhere. I tried to hedge the
phrasing in 5.5 to spare myself mentioning both forms of instanceof, but
perhaps it would just be clearer to do so.
Thanks.
Gavin
