Annos on records

[Brian Goetz]

And MR-Jar obviates using ASM to add the right value to the 
meta-annotation; you just have two sources, one for 13 and one for prior.

On 4/10/2018 5:07 PM, Remi Forax wrote:
> Here is what i've done to support ElementType.MODULE a library that 
> has to work with Java 8,
> adding a target type is usually compatible because the one that add 
> the annotation target is often the one in control of the code that 
> will also consume the annotation.
>
> In order to work you need to answer two questions:
>   - how to create an annotation compatible 8 with a meta-annotation 
> value only available in 9.
>     using ASM to add the right value to the annotation meta-annotation 
> is a 10 lines program,
>  - how to consume a non existing meta-annotation value,
>    i do a switch on the name of the enum instead of doing a switch on 
> the enum itself.
>
> Rémi
>
> ------------------------------------------------------------------------
>
>     *De: *"Kevin Bourrillion" <kevinb at google.com>
>     *À: *"Brian Goetz" <brian.goetz at oracle.com>
>     *Cc: *"amber-spec-experts" <amber-spec-experts at openjdk.java.net>
>     *Envoyé: *Mardi 10 Avril 2018 22:42:24
>     *Objet: *Re: Annos on records (was: Records -- Using them as JPA
>     entities and validating them with Bean Validation)
>
>     If we create a new ElementType.RECORD, the annotation in question
>     won't even be /able /to add that target type until it is ready to
>     /require/ JDK 13 (or whatever) as its new minimum version.
>
>
>     On Tue, Apr 10, 2018 at 1:38 PM, Brian Goetz
>     <brian.goetz at oracle.com <mailto:brian.goetz at oracle.com>> wrote:
>
>         [ moving to amber-spec-experts]
>
>         I tend to agree.  It will take longer to adopt, but it _is_ a
>         new kind of target in a source file, and then frameworks can
>         decide what it should mean, and then there's no confusion.
>
>         It's possible, too, as a migration move, to split the
>         difference, though I'm not sure its worth it -- add a new
>         target, _and_, if the target includes param/field/method, but
>         does _not_ include record, then lower the anno onto all
>         applicable members.
>
>         On 4/10/2018 1:34 PM, Remi Forax wrote:
>
>             No, not right for me,
>             a new Annotation target is better so each framework can
>             decide what it means for its annotation.
>
>             It will slow the adoption but it's better in the long term.
>
>             Rémi
>
>             ----- Mail original -----
>
>                 De: "Kevin Bourrillion" <kevinb at google.com
>                 <mailto:kevinb at google.com>>
>                 À: "Gunnar Morling" <gunnar at hibernate.org
>                 <mailto:gunnar at hibernate.org>>
>                 Cc: "amber-dev" <amber-dev at openjdk.java.net
>                 <mailto:amber-dev at openjdk.java.net>>
>                 Envoyé: Mardi 10 Avril 2018 19:25:57
>                 Objet: Re: Records -- Using them as JPA entities and
>                 validating them with Bean Validation
>                 On Mon, Apr 9, 2018 at 1:39 PM, Gunnar Morling
>                 <gunnar at hibernate.org <mailto:gunnar at hibernate.org>>
>                 wrote:
>
>                        * Annotation semantics: I couldn't find any
>                     example of records with
>                     annotations, but IIUC, something like
>
>                              @Entity record Book(@Id long id, String
>                     isbn) { ... }
>
>                          would desugar into
>
>                              class @Entity public class Book { private
>                     @Id long id, private
>                     String isbn; ... };
>
>                          For the JPA entity use case it'd be helpful
>                     to have an option to lift
>                     annotations to the corresponding getters instead
>                     of the fields (as the
>                     location of the @Id annotation controls the
>                     default strategy -- field vs.
>                     property -- for reading/writing entity state).
>                     Similarly, Bean Validation
>                     would benefit from such option.
>
>                 My assumption has been that we would allow an
>                 annotation on a record
>                 parameter as long as it has *any of
>                 *{FIELD,METHOD,PARAMETER} as target,
>                 and that the annotation would be automatically
>                 propagated to each
>                 synthesized element it applies to. Does this sound
>                 about right to everyone?
>
>
>                 --
>                 Kevin Bourrillion | Java Librarian | Google, Inc. |
>                 kevinb at google.com <mailto:kevinb at google.com>
>
>
>
>
>
>     -- 
>     Kevin Bourrillion | Java Librarian | Google,
>     Inc. |kevinb at google.com <mailto:kevinb at google.com>
>

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