10:46 a.m.
Hi Mark, I'll try to answer inline, but I'm missing a bit of background about what
you are doing...
On 4 Dec 2012, at 14:20, Mark Struberg wrote:
Another problem probably being an interceptor on the @Disposes method
itself.
Where does the Proucer#dispose(T instance) get the interceptor from?
LieGrue,
strub
----- Original Message -----
> From: Mark Struberg <struberg(a)yahoo.de>
> To: cdi-dev <cdi-dev(a)lists.jboss.org>
> Cc:
> Sent: Tuesday, December 4, 2012 3:16 PM
> Subject: [cdi-dev] Producer#dispose(T instance) and similar
>
> Hi!
>
> I'm currently stumbling over implementing
>
> Producer#dispose(T instance) properly
>
> The Producer#produce(CreationalContext)
>
> has the CreationalContext parameter but the dispose
Right, it would have been good to have included it here. I'm not sure why it
wasn't, however I don't believe that it causes a problem with the CDI 1.0 spec,
but just limits us going forward.
> and others do not have it.
Yes.
>
> Problem here is that a Producer could probably get exchanged via a portable
> extension via ProcessProducer#setProducer(Producer)
Yes, this is definitely supported
> so it could be from a
> foreign source which must not know anything about container implementation
> details.
Yes.
I think the critical part of the spec to understand this is 11.2. I'm quoting here
from the CDI 1.1 spec, into which we have add the clarification that "The instance
returned by produce() may be a proxy.". The part about building interceptors and
decorators is there in CDI 1.0.
For a Producer that represents a class:
• produce() calls the constructor annotated @Inject if it exists, or the constructor
with no parameters otherwise, as defined in [instantiation], and returns the resulting
instance. If the class has interceptors,produce() is responsible for building the
interceptors and decorators of the instance. The instance returned by produce() may be a
proxy.
• dispose() does nothing.
and
For a Producer that represents a producer method or field:
• produce() calls the producer method on, or accesses the producer field of, a
contextual instance of the bean that declares the producer method, as defined in
[methods].
• dispose() calls the disposer method, if any, on a contextual instance of the bean that
declares the disposer method, as defined in [methods], or performs any additional required
cleanup, if any, to destroy state associated with a resource.
Now, let me start to break down your sentence :-)
>
> What now about having an interceptor on @PreDestroy?
For a start, it's worth remembering interceptors can only be associated with beans
defined by a class. If the bean is a producer, then you can't intercept the instance
produced (only the invocation of the producer).
> This is what you get if
> your interceptor has a@PreDestroy method himself as per the interceptors and EJB
> specs. That would mean that the instance passed to dispose() whould be the
> proxy? That purely sounds wrong to me.
Based on my comment from above, I think it's clear that dispose() should never try to
invoke predestroy methods. That is the job of InjectionTarget.preDestroy(). I would expect
a proxy to be passed to preDestroy().
>
> Another issue being InjectionTarget#postConstruct() only having the instance T
> as well. Now what about @PostConstruct interceptors as defined in the
> interceptors spec?
Again, I would expect a proxy to be passed to postConstruct(). Anyway, I'm not sure
why you need access to the creational context in the postConstruct()? Here you should just
invoke the postConstruct callback, which should create any new dependent objects.
> Currently we have a dirty hack in OWB to pass over the
CreationalContext which
> contains the dependent scoped interceptors for our own Producers and
> InjectionTargets. But I have no clue yet how that should get implemented if one
> plugs in a portable Producer via an Extension ^^
>
> Who is responsible of performing the interception? The Producer? Or must the
> instance being handed into already be a Proxy?
The instance returned from produce() should have interceptors and decorators applied.
Please let me know if above makes sense, it took me a while to work out whether what was
defined was sane. After quite a lot of thinking + talking to Jozef and Stuart I came to
the conclusion it was, but if you can poke holes then please do!