[cdi-dev] [JBoss JIRA] (CDI-686) Could InterceptionFactory accept an interface as type parameter

[Matej Novotny (Jira)]

    [ https://issues.jboss.org/browse/CDI-686?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13691952#comment-13691952 ] 

Matej Novotny commented on CDI-686:
-----------------------------------

I have taken a stab at this with Weld 3.1.0.Final and managed to come up with a working prototype that can base {{InterceptionFactory}} off an interface while providing even unproxyable instance in the end. So it's definitely possible yet comes with many question marks attached. Here are  some from the top of my head with my thoughts on them:
* What about the interceptor binding(s) on the implementation class? Do you retain them or toss them away?
** IMO toss away, since it can be unproxyable, there is no reason to have them there in the first place
* What about binding on interface itself?
** There is a possibility that the interface has some bindings, but CDI disregards annotations on interfaces in general, I would do the same here
** Accepting those would also introduce a problem of clashes in values if you try to programatically add the same annotation that is already present on the interface
* What about hierarchies of interfaces - what if I add a class-level binding programatically, does it apply to methods from this interface's predecessors that weren't overriden?
** Here I honestly don't know, I went with _no_ in the first draft just because it required extra magic to make that happen and it's a corner case

> Could InterceptionFactory accept an interface as type parameter
> ---------------------------------------------------------------
>
>                 Key: CDI-686
>                 URL: https://issues.jboss.org/browse/CDI-686
>             Project: CDI Specification Issues
>          Issue Type: Clarification
>    Affects Versions: 2.0 .Final
>            Reporter: Antoine Sabot-Durand
>            Assignee: Antoine Sabot-Durand
>            Priority: Major
>             Fix For: 2.0 .Final
>
>
> If you take this code:
> {code:java}
>     @Produces
>     public List<Object> produceList(InterceptionFactory<List<Object>> interceptionFactory) {
>         interceptionFactory.ignoreFinalMethods().configure().filterMethods((m) -> {
>             if (m.getJavaMember().getName().equals("add")
>                     && m.getJavaMember().getParameterCount() == 1) {
>                 return true;
>             }
>             return false;
>         }).findFirst().get().add(Monitor.Literal.INSTANCE);
>         return interceptionFactory.createInterceptedInstance(new ArrayList<>());
>     }
> {code}
> Parameterized type for injected {{InterceptionFactory}} is an interface {{List<Object>}}, so when calling {{configure()}}, user will work with an {{AnnotatedTypeConfigurator<List<Object>>}} to apply interceptor binding.
> In a standard interceptor usage, interceptor binding on interface are ignored (even if they have {{@Inherited}} annotation), so doing it with {{InterceptionFactory}} could be confusing for some user.



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