[weld-issues] [JBoss JIRA] Created: (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
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.
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