[webbeans-dev] producer method trumps raw dependent type?

[Pete Muir]

Probably a good FAQ http://www.seamframework.org/Documentation/WebBeans
On 22 Jul 2009, at 15:05, Dan Allen wrote:

> Okay, so there is an explicit step that must be taken for a producer  
> method to win over a @Current bean (does not have additional  
> bindings) of that type. I suspect in most cases developers will  
> choose to use the binding type since that is the type-safe approach.
>
> The designation of the alternative class in beans.xml makes all  
> producer methods in that class have a higher precedence than any  
> @Current bean of that type, correct? Is it also possible to specify  
> a single method in beans.xml? There is alluded to in the Policy  
> section, but no examples to support it.
>
> Btw, I think this would be a lot clearer if it was explicitly stated  
> in the spec how a producer method relates to a @Current bean of that  
> type. I guess you could say it can be implied, but the first time  
> someone goes to create a producer method, I can see them not  
> realizing that they have to take an extra step to make it the  
> preferred source.
>
> -Dan
>
> On Wed, Jul 22, 2009 at 7:13 AM, Pete Muir <pmuir at redhat.com> wrote:
>
> On 22 Jul 2009, at 03:18, Dan Allen wrote:
>
> After the recent revisions of the JSR-299 spec, I'm finding that I'm  
> a tad confused about the bean selection algorithm when a producer  
> method exists.
>
> Consider the following:
>
> class PotatoChip {
> }
>
> class SnackFactory() {
>    public @Produces PotatoChip createPotatoChip() {
>        return new PotatoChip();
>    }
> }
>
> 1) Does the produced PotatoChip take precedence over the raw  
> dependent type when being selected for injection?
>
> No.
>
>
>
> 2) How do I get the Bean<PotatoChip> that represents the producer  
> method?
>
> BeanManager#getBeans(PotatoChip.class) returns two beans that are  
> indistinguishable from the public API.
>
> either:
>
> @Alternative
>
> class SnackFactory() {
>    public @Produces PotatoChip createPotatoChip() {
>        return new PotatoChip();
>    }
> }
>
> <beans>
>   <alternatives>
>      <alternative>SnackFactory</alternative>
>   </alternatives>
> </beans>
>
> or
>
> class SnackFactory() {
>    public @Produces @Snack PotatoChip createPotatoChip() {
>        return new PotatoChip();
>    }
> }
>
> BeanManager.getBeans(PotatoChip.class, new  
> AnnotationLiteral<Snack>() {});
>
> where @Snack is a binding type
>
>
>
> 3) What if the producer method is @RequestScoped? How do I get the  
> request-scoped produce instead of the dependent bean?
>
>      Bean<PotatoChip> potatoChipBean = null;
>      for (Bean<PotatoChip> candidate : getBeans(PotatoChip.class))
>      {
>         if (candidate.getScopeType().equals(RequestScoped.class))
>         {
>            potatoChipBean = candidate;
>            break;
>         }
>      }
>
> Sorry if this sounds like a dumb question. The spec has changed a  
> lot and my memory is getting mixed in with the current set of facts.
>
> As above.
>
> It's possible the RI doesn't actually reflect this behavior atm - if  
> you have a problem, make sure there is a test, then change the RI or  
> file a WBRI.
>
>
>
> -- 
> Dan Allen
> Senior Software Engineer, Red Hat | Author of Seam in Action
> Registered Linux User #231597
>
> http://mojavelinux.com
> http://mojavelinux.com/seaminaction
> http://in.relation.to/Bloggers/Dan
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