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

[Martin Kouba (JIRA)]

    [ https://issues.jboss.org/browse/CDI-628?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13290442#comment-13290442 ] 

Martin Kouba commented on CDI-628:
----------------------------------

Just a note - JMS wording and solution/impl is IMHO also not correct from the CDI point of view. Because, for the same IP you should get different beans depending on the TX status and this is normally an ambiguous resolution, so they have to implement some kind of delagation bean injected and forwarding the calls to either {{@RequestScoped}} or {{@TransactionScoped}} implementation.

> 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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