[cdi-dev] [JBoss JIRA] (CDI-628) Allow overriding of Scope at Injection Point

[John Ament (JIRA)]

    [ https://issues.jboss.org/browse/CDI-628?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13290414#comment-13290414 ] 

John Ament commented on CDI-628:
--------------------------------

It is possible to create a bean via a portable extension that has two different scopes - two different beans.  The JMS spec leverages this to allow JMSContext to be injectable for both request scoped and transaction scoped.  

I would recommend that approach over the injection point overriding the scope.

> Allow overriding of Scope at Injection Point
> --------------------------------------------
>
>                 Key: CDI-628
>                 URL: https://issues.jboss.org/browse/CDI-628
>             Project: CDI Specification Issues
>          Issue Type: Feature Request
>    Affects Versions: 2.0 (proposed)
>            Reporter: Stephan Knitelius
>            Priority: Minor
>
> Allow overriding scopes at injection point.
> {code}
> @SessionScope
> public class FeatureState {...}
> public class Bean B {
>   @Inject
>   @ConversationScoped //Overriding original scope
>   public BeanA beanA;
>   ...
> }
> {code}
> Sample use-case for for a feature flag:
> {code}
> @Alternative
> public class FeatureStateProducer {
>   @Inject
>   @SessionScoped
>   private FeatureState devState;
>   @Inject
>   @ConversationScoped
>   private FeatureState viewState;
>   @Inject
>   private JNDIProvider jndiProvider;
>   private boolean viewOnly = true;
>   @PostConstruct
>   public void postConstruct() {
>     this.viewMode = ...; //read config.
>   }
>   @Produces
>   public FeatureState produce() {
>     return viewOnly ? viewState : devState;
>   }
> }
> {code}
> Currently this can be solved by overriding scope with @Qualifiers:
> {code}
> @ViewMode
> @ConversationScoped
> public class ViewFeatureState extends FeatureState {...}
> @DevMode
> @SessionScoped
> public class DevFeatureState extends FeatureState {...}
> {code}
> Risks:
> * developers might start to define the scopes at IP and on bean (hard to maintain).
> * confusing when debugging, annotation on bean, e.g. @ApplicationScoped yet behaving differently.
> * etc... 



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