[weld-issues] [JBoss JIRA] Commented: (WELD-218) Check and fix if type variables are allowed on observes methods

Check and fix if type variables are allowed on observes methods --------------------------------------------------------------- Key: WELD-218 URL: https://jira.jboss.org/jira/browse/WELD-218 Project: Weld Issue Type: Feature Request Affects Versions: 1.0.0.CR1 Reporter: Kabir Khan Priority: Critical Fix For: 1.0.0.CR2 Kabir: I have tried; public void processInjectionTarget(@Observes ProcessInjectionTarget<?> event) { AnnotatedType<?> type = event.getAnnotatedType(); WeldKernelControllerContext context = WeldFromMcRegistry.getContext(type); if (context != null) { InjectionTarget<?> target = event.getInjectionTarget(); @SuppressWarnings("unchecked") ExistingInstanceInjectionTarget<?> wrappedTarget = new ExistingInstanceInjectionTarget(target, context.getTarget()); event.setInjectionTarget(wrappedTarget); } } This does not compile with the error: The method setInjectionTarget(InjectionTarget<capture#6-of ?>) in the type ProcessInjectionTarget<capture#6-of ?> is not applicable for the arguments (ExistingInstanceInjectionTarget<capture#7-of ?>) Pete: Yes, this is the correct approach, as it will observe all events. Kabir: However, the call to event.setInjectionTarget() does not compile in this case. I've had to do the following: public void processInjectionTarget(@Observes @SuppressWarnings("unchecked") ProcessInjectionTarget event) { AnnotatedType<?> type = event.getAnnotatedType(); WeldKernelControllerContext context = WeldFromMcRegistry.getContext(type); if (context != null) { InjectionTarget<?> target = event.getInjectionTarget(); @SuppressWarnings("unchecked") ExistingInstanceInjectionTarget tgt = new ExistingInstanceInjectionTarget(target, context.getTarget()); event.setInjectionTarget(tgt); } } Pete: Ok, this is fixable if type variables are allowed on observes methods. Kabir: public <X> void processInjectionTarget(@Observes ProcessInjectionTarget<X> event) { AnnotatedType<?> type = event.getAnnotatedType(); WeldKernelControllerContext context = WeldFromMcRegistry.getContext(type); if (context != null) { InjectionTarget<X> target = event.getInjectionTarget(); ExistingInstanceInjectionTarget<X> wrappedTarget = new ExistingInstanceInjectionTarget<X>(target, context.getTarget()); event.setInjectionTarget(wrappedTarget); } } which compiles, but gives: org.jboss.weld.DefinitionException: Cannot use a type variable X in an parameterized type Observer Implementation: Observer (Declaring) class: class org.jboss.test.kernel.weld.mctowb.support.validateobserver.TestObserver Observer method: method public void org.jboss.test.kernel.weld.mctowb.support.validateobserver.TestObserver.processInjectionTarget(javax.enterprise.inject.spi.ProcessInjectionTarget) at org.jboss.weld.event.ObserverMethodImpl.checkObserverMethod(ObserverMethodImpl.java:118) at org.jboss.weld.event.ObserverMethodImpl.initialize(ObserverMethodImpl.java:191) Pete: I *believe* this is a bug in the RI. Could you do me a favour, and scour the Events chapter, and make sure it doesn't restrict you from putting a parameterized type in an @Observes parameter? If it doesn't, file a bug for CR2. I will fix it asap. Kabir: I'm not 100% sure, but I don't think I saw anything there regarding type variables.