[cdi-dev] Adding Lambdas as CDI beans

[Romain Manni-Bucau]

would be super cool to not have to write an extension for that, cant we use
applicationscope init event or an prioritized event at this moment -
avoiding the spi is a must for end user usage IMO?


Romain Manni-Bucau
@rmannibucau <https://twitter.com/rmannibucau> |  Blog
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2015-10-19 8:40 GMT+02:00 Martin Kouba <mkouba at redhat.com>:

> 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 at gmail.com
> > <mailto:david.blevins at 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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> >
> >
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>
> --
> Martin Kouba
> Software Engineer
> Red Hat, Czech Republic
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