[weld-dev] Is an interceptor with @Target(METHOD, CONSTRUCTOR, TYPE) a problem?

[Marius Bogoevici]

On 2010-07-18, at 9:04 AM, Pete Muir wrote:

> Whatever, this is a poor error message!
> 

The error message is correct for situations when the interceptor has no bindings - which is a violation of the spec. 

In this scenario, we're hitting an ambiguity in the specification: the only thing it says about bindings is that they can have as target only types and/or methods, but doesn't say what happens when this provision is violated. 

In this case we can have a few options: 
a) treat the offending annotation as "not a binding" and issue a warning (the current logging level is DEBUG, but should be WARN). What happens is that the annotation is effectively ignored as an interceptor binding. 
b) throw a deployment error complaining about the binding being invalid - trouble is, that this is uncalled for by the specification;
c) ignore the fact that the binding has extra targets;

a) is more lenient, but can also be more confusing. We can 'fix' the error message by explaining that the issue may be caused by an invalid InterceptionBinding, but this will still be a problem if we have *two* bindings,  of which one is valid - no error message is shown, but the behaviour will not be the one expected. 

c) is more lenient too, but allowing to place a binding on something else than a method or type is plainly wrong.

So, unless there are strong objections to it, I will switch to b), since there's no good way of making clear that the binding annotation is ignored (the warning is the best thing that we can do, but it's easy to loose track of it). Also, this is effectively an error, since it's an attempt to use the CDI API in ways that are not intended to be supported. I also think that we should capture this a spec revision.



> Marcin, could you file an issue in WELD please?
> 
> On 18 Jul 2010, at 03:03, Marius Bogoevici wrote:
> 
>> Hi Marcin,
>> 
>> Only annotations with @Target({ElementType.METHOD, ElementType.TYPE}) or @Target({ElementType.TYPE}) can be interceptor bindings (chapter 1 of the spec).
>> 
>> CDI interceptors cannot be defined for constructors per se (so there's no around-constructor semantics), but you can have a @PostConstruct method on a @Target({ElementType.TYPE}) interceptor, which effectively executes after the instance has been created and CDI-injected.
>> 
>> Hope this helps,
>> Marius
>> 
>> On 2010-07-17, at 5:36 PM, Marcin Zajączkowski wrote:
>> 
>>> Hi,
>>> 
>>> 
>>> I'm trying to write mocked unit tests for my interceptor using
>>> mechanisms given by AbstractWeldTest and jboss-test-harness package.
>>> 
>>> My test class extends AbstractWeldTest, had Artifact and WebBeans
>>> (pointing to beans.xml with my interceptor defined) annotations.
>>> 
>>> My interceptor seems normal for me:
>>> @Target({ElementType.METHOD, ElementType.CONSTRUCTOR, ElementType.TYPE})
>>> @Retention(RetentionPolicy.RUNTIME)
>>> @InterceptorBinding
>>> public @interface Perf4jProfiled {
>>> }
>>> 
>>> When I run a very simple test, I've got:
>>> 23:06:53.505 [main] DEBUG org.jboss.weld.Reflection - WELD-000602
>>> interface net.sf.perf4cdi.api.Perf4jProfiled is not declared
>>> @Target(TYPE, METHOD) or @Target(TYPE)
>>> org.jboss.weld.exceptions.DeploymentException: WELD-000069 An
>>> interceptor must have at least one binding, but
>>> net.sf.perf4cdi.Perf4jProfiledInterceptor has none
>>> 	at org.jboss.weld.bean.InterceptorImpl.<init>(InterceptorImpl.java:71)
>>> 	at org.jboss.weld.bean.InterceptorImpl.of(InterceptorImpl.java:55)
>>> 	at
>>> org.jboss.weld.bootstrap.AbstractBeanDeployer.createInterceptor(AbstractBeanDeployer.java:255)
>>> 	at org.jboss.weld.bootstrap.BeanDeployer.createBeans(BeanDeployer.java:106)
>>> 	at
>>> org.jboss.weld.bootstrap.BeanDeployment.deployBeans(BeanDeployment.java:151)
>>> 	at
>>> org.jboss.weld.bootstrap.WeldBootstrap.deployBeans(WeldBootstrap.java:377)
>>> 	at
>>> org.jboss.weld.mock.MockServletLifecycle.beginApplication(MockServletLifecycle.java:121)
>>> 	at org.jboss.weld.mock.TestContainer.startContainer(TestContainer.java:85)
>>> 	at
>>> org.jboss.weld.test.harness.AbstractStandaloneContainersImpl.deploy(AbstractStandaloneContainersImpl.java:40)
>>> 	at org.jboss.testharness.AbstractTest.deployArtifact(AbstractTest.java:103)
>>> 	at org.jboss.testharness.AbstractTest.beforeClass(AbstractTest.java:206)
>>> 	at
>>> org.jboss.weld.test.AbstractWeldTest.beforeClass(AbstractWeldTest.java:57)
>>> 
>>> 
>>> When I remove CONSTRUCTOR it works better (there is another problem, but
>>> not related I have to debug it).
>>> 
>>> I would like to ask if this is a limitation of CDI that an interceptor
>>> cannot be put on constructor?
>>> 
>>> 
>>> Regards
>>> Marcin
>>> 
>>> _______________________________________________
>>> weld-dev mailing list
>>> weld-dev at lists.jboss.org
>>> https://lists.jboss.org/mailman/listinfo/weld-dev
>> 
>> 
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