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]
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(a)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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