Annotating lambda expressions

[Ron Pressler]

Allowing annotations on lambda expressions but not on method references
seems very reasonable to me. Manual expansion of the method reference into
an expression is always possible.

Ron Pressler
paralleluniverse.co
@puniverseco <https://twitter.com/puniverseco> on Twitter

On Fri, Jul 10, 2015 at 12:31 PM, Maurizio Cimadamore <
maurizio.cimadamore at oracle.com> wrote:

>
>
> On 10/07/15 09:43, Ron Pressler wrote:
>
>> (Related to
>> http://mail.openjdk.java.net/pipermail/compiler-dev/2015-January/009220.html)
>>
>>
>> It is useful to add an annotation to a lambda expression -- as in
>> foo(@Special () -> { ...}) -- which will be applied to the static method
>> implementing the lambda (not to the interface the lambda implements). This
>> would allow instrumentation tools operating on method implementations to
>> handle lambdas. So far, AFAICT, this is not possible (or am I wrong?).
>>
> This is not possible, currently - as Remi said; you have annotations on
> declarations (i.e. variable, classes, methods) - you have annotation on
> types (i.e. type of a cast, type argument, etc.) - but you don't have
> annotations on _expressions_.
> I take it that, under the current translation scheme, there seems to be a
> plausible description for what should happen when the lambda is annotated;
> but what if the lambda is turned into a method reference (by some IDE
> refactoring, or human intervention) ? In that case it is not guaranteed
> that there would still be a physical place where to put the annotation
> (unless we tell the compiler to 'expand' all annotated method references).
>
> So, while I don't question the genuine nature of the use case you put
> forward, I'm not seeing a 100% straightforward path to get there w/o adding
> non trivial complexity to both implementation and the spec.
>
> Maurizio
>
>>
>> Opinions?
>>
>> Ron
>>
>
>
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