In CDI 2.0 we propose to support lambdas in the bean builder API -
currently available as a weld experimental feature in AfterBeanDiscovery
and Weld SE - see also [1] and [2].

For observers a similar builder might be useful.

Martin

[1]
http://weld.cdi-spec.org/news/2015/02/25/weld-300Alpha5/#_bean_builder_api

[2]
https://github.com/weld/core/blob/master/tests-arquillian/src/test/java/org/jboss/weld/tests/extensions/custombeans/BuilderExtension.java



Dne 17.10.2015 v 13:51 Sven Linstaedt napsal(a):
> Just one question: Who is on charge and is able of managing this
> unmanaged instances, e.g. lifecycle, serialization, concurrency (e.g.
> when dealing with closures)?
>
> Functional programming and DI seem to be somehow disjunct in this case.
> E.g. manually setting up observers seem to better fit extension than
> normal application code.
>
> On the other side, specifying producer methods or fields, that are
> injectable and return lambda expressions seems to be a no brainier for
> CDI, is not it? As long as they are not scoped in a serializable context.
>
> Have a nice weekend
> Sven
>
> -- sent by phone
>
> Am 17.10.2015 um 11:06 schrieb David Blevins <david.blevins@gmail.com
> <mailto:david.blevins@gmail.com>>:

>
>> In brainstorming mode about fun that could be made possible with Java
>> 8 and Java EE.
>>
>> Question in my mind is: is there some way we could make it possible
>> for Lambdas or Method Refs to be CDI beans?
>>
>> It goes against the grain obviously as CDI creation is very much a
>> “Don’t call us, we’ll call you” kind of thing.  The VM dynamically
>> creates a wrapper object around the Lambda or method reference and it
>> implements the given interface.
>>
>> To make it work, there would need to be some non-producer method way
>> of saying “put this thing in the context with these qualifiers”.
>>
>> Imagine a method somewhere that would allow you to:
>>
>>    public <T> void addObserver(java.util.function.Consumer<T>
>> observer, Annotation... qualifiers);
>>
>>
>> Then you could take advantage as follows:
>>
>>    final List<URI> uris = new ArrayList<>();
>>    // @Observes URI
>>    addObserver((Consumer<URI>) uris::add);
>>
>>    // @Observes Thread
>>    addObserver(Runtime.getRuntime()::addShutdownHook);
>>
>>    // @Observes Runnable
>>    addObserver((Consumer<Runnable>)
>> Executors.newFixedThreadPool(3)::submit);
>>
>>    // @Observes URI
>>    addObserver((Consumer<URI>) System.out::println, new
>> AnnotationLiteral<Fine>() {
>>    });
>>
>>    // @Observes Handler
>>    final Logger logger = Logger.getLogger("somewhere");
>>    addObserver(logger::addHandler); // add handlers via event
>>
>>    // @Observes @Fine String
>>    addObserver((Consumer<String>) logger::fine, new
>> AnnotationLiteral<Fine>() {});
>>    }
>>
>>
>>
>> -David
>>
>>
>>
>> --
>> David Blevins
>> http://twitter.com/dblevins
>> http://www.tomitribe.com
>>
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--
Martin Kouba
Software Engineer
Red Hat, Czech Republic

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