[cdi-dev] Portable decorable Bean<T> instances

[Martin Kouba]

Dne 10.7.2018 v 13:45 arjan tijms napsal(a):
> Hi,
> 
> Thanks for the reply. I already feared that to be the answer.
> 
> This would probably be a good enhancement request for CDI 2.1. At the 
> very least the BeanConfigurator could have a method like 
> BeanConfigurator#setDecorators<Decorator<?>... decorators. That's 
> seemingly doable to implement by the CDI implementations.

Well, it's not that simple. In order to make decorators work the 
instance produced by Bean#create(CreationalContext<T>) must be proxied, 
decorated types only include interfaces, etc.

There are few issues related to this topic. I'd suggest to walk through 
all those issues, close duplicates and outdated issues and create a new 
one with distilled summary...

> 
> Kind regards,
> Arjan
> 
> 
> 
> 
> 
> On Tue, Jul 10, 2018 at 11:04 AM Matej Novotny <manovotn at redhat.com 
> <mailto:manovotn at redhat.com>> wrote:
> 
>     Hi,
> 
>     yes, there is no portable way.
>     It is a similar situation as was with interceptors before
>     InterceptionFactory was added.
> 
>     [impl 'details']
>     In principle, to implement this, you need to create a "wrapper
>     class" around the object which is to be intercepted/decorated.
>     If you provide a custom way to create the bean, it is very difficult
>     to create this wrapper on-the-fly.
>     Even the solution for interceptors has some shortcomings and flaws
>     and decorators seem even more complex (less restrictions on how does
>     a decorator look like).
> 
>     Matej
> 
>     ----- Original Message -----
>      > From: "arjan tijms" <arjan.tijms at gmail.com
>     <mailto:arjan.tijms at gmail.com>>
>      > To: cdi-dev at lists.jboss.org <mailto:cdi-dev at lists.jboss.org>
>      > Sent: Tuesday, July 10, 2018 11:30:54 AM
>      > Subject: [cdi-dev] Portable decorable Bean<T> instances
>      >
>      > Hi,
>      >
>      > When adding a manually constructed Bean<T> instance using
>      > AfterBeanDiscovery.addBean(Bean<?>), or using the
>      > AfterBeanDiscovery.addBean() method and the BeanConfigurator, the
>     resulting
>      > bean can't be decorated.
>      >
>      > This is because seemingly CDI expects the create() method of
>     Bean<T> to
>      > locate the decorators itself and apply them to the instance it
>     returns.
>      >
>      > Using BeanManager.resolveDecorators one can obtain the Decorator<T>
>      > instances, but am I right that there's no portable way to
>     actually apply
>      > those decorators to the bean instance?
>      >
>      > Kind regards,
>      > Arjan
>      >
>      >
>      >
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> 
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-- 
Martin Kouba
Senior Software Engineer
Red Hat, Czech Republic