Draft JEP on Primitive types in patterns, instanceof, and switch

[Kevin Bourrillion]

Depending on float equality is *dangerous*, but doesn't completely lack
valid use cases.

Doing so in this manner doesn't seem fundamentally different from all the
other ways you can do it too; in my world, *any* of these ways will earn
you a static analysis warning. The user can suppress that, and I think this
is a wholly reasonable arrangement.


On Thu, Jan 26, 2023 at 9:26 AM Per-Ake Minborg <per-ake.minborg at oracle.com>
wrote:

> Maybe certain values for float and double should be allowable (e.g. NaN
> (matching all variants), POSITIVE_INFINITY, NEGATIVE_INFINITY and zero
> (matching any zero value))? These are clearly defined. All other values
> would render a compile-time error? (many question marks here) /P
> ------------------------------
> *From:* amber-dev <amber-dev-retn at openjdk.org> on behalf of Remi Forax <
> forax at univ-mlv.fr>
> *Sent:* Thursday, January 26, 2023 2:15 PM
> *To:* Angelos Bimpoudis <angelos.bimpoudis at oracle.com>
> *Cc:* amber-dev <amber-dev at openjdk.org>
> *Subject:* Re: Draft JEP on Primitive types in patterns, instanceof, and
> switch
>
>
>
> ------------------------------
>
> *From: *"Angelos Bimpoudis" <angelos.bimpoudis at oracle.com>
> *To: *"amber-dev" <amber-dev at openjdk.org>
> *Sent: *Thursday, January 26, 2023 10:48:47 AM
> *Subject: *Draft JEP on Primitive types in patterns, instanceof, and
> switch
>
> Hello all,
>
> I would like to share this draft JEP with you about primitive types in
> patterns, instanceof, and switch:
>
> https://openjdk.org/jeps/8288476
>
> "Enhance pattern matching by allowing primitive types to appear anywhere
> in patterns. Extend instanceof to support primitive types, and extend
> switch to allow primitive constants as case labels."
>
> Comments very much welcomed!
>
> Many thanks,
> Angelos
>
>
> I still think that the semantics proposed for pattern matching on
> primitive types is useless complexity with the perverse side effect of
> normalizing the usage of "default" in pattern matching (too many examples
> of this JEP are using "default") but we already discussed that.
>
> Allowing switching on double and float constants is just wrong.
> Rust is actually trying to remove that feature
>   https://github.com/rust-lang/rust/issues/41255
>
> I see no point to make the same mistake.
>
> Otherwise, the rest is fine.
>
> Rémi
>
>

-- 
Kevin Bourrillion | Java Librarian | Google, Inc. | kevinb at google.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/amber-dev/attachments/20230126/9b2ebfb1/attachment-0001.htm>