[cdi-dev] CDI and generics

[Martin Kouba]

Hi Arne,

I think so (except the required type is Baz<List<Qux>>) - there is no
bean with assignable bean type for this IP (according to CDI 1.1 rules
of course).

Martin

Dne 10.7.2013 13:16, Arne Limburg napsal(a):
> Hi Martin,
> 
> So, which bean should be injected into
> @Inject
>     private Baz<List<T2>> t2BazList;
> ?
> 
> Baz<T> is also not assignable to Baz<List<String>>, because List<String>
> is also not assignable from Object.
> 
> 
> Am I right, that the test should throw an UnsatisfiedResolutionException?
> 
> Cheers,
> Arne
> 
> Am 08.07.13 12:17 schrieb "Martin Kouba" unter <mkouba at redhat.com>:
> 
>> Re Arne's question:
>> Yes, Baz is a managed bean and AmbiguousResolutionException should not
>> be thrown because Qux is not a managed bean (doesn't have a public
>> no-arg constructor).
>>
>> Re Marko's findings:
>> Yes, the TCK assertions are not up to date and Baz<T> is not assignable
>> to Baz<String>, because String is not assignable from Object (no bound
>> is defined -> Object is assumed; see JSL 4.4). So I confirm a TCK issue.
>>
>> IMO this would deserve a proper cleanup...
>>
>> Martin
>>
>> Dne 8.7.2013 01:22, Marko Lukša napsal(a):
>>> I'd say it's a bug. While Baz indeed is a managed bean, it shouldn't be
>>> injected into injection point with type Baz<String> nor Baz<List<Qux>>.
>>> So I believe you're right in saying that this test should fail with
>>> UnsatisfiedResolutionException.
>>>
>>> There was a change made to the spec way back in 2010 (see [1]), but the
>>> TCK apparently wasn't updated then. I've filed an issue in the TCK jira
>>> [2].
>>>
>>> The problem isn't only in the TCK, but also in the spec itself. Some of
>>> the examples in section 5.2.4 don't conform to the rules defined in the
>>> same section (according to the rules, bean Dao<T extends Persistent>
>>> shouldn't be eligible for injection into Dao<Order> or Dao<User>). I
>>> remember asking about this a year ago ([3]), but I didn't articulate the
>>> problem properly.
>>>
>>> [1]
>>>
>>> https://github.com/cdi-spec/cdi/commit/b32243350ace6a0bba337f91a35f5fd05c
>>> 151f14
>>> [2] https://issues.jboss.org/browse/CDITCK-349
>>> [3] http://lists.jboss.org/pipermail/cdi-dev/2012-April/001742.html
>>>
>>> Marko
>>>
>>> On 7.7.2013 16:04, Arne Limburg wrote:
>>>> Hi all,
>>>>
>>>> At the OpenWebBeans list we are currently discussing handling of
>>>> generics in CDI.
>>>> I found a test in the CDI 1.1 TCK, which imho has a bug. The test
>>>> is 
>>>> org.jboss.cdi.tck.tests.inheritance.generics.MemberLevelInheritanceTest
>>>> and the (simplified) deployment scenario is the following:
>>>>
>>>> public class Baz<T> {
>>>> }
>>>>
>>>> public class Qux extends Baz<String> {
>>>> }
>>>>
>>>> @Vetoed
>>>> public class Bar<T1, T2> {
>>>>   @Inject
>>>>   private Baz<T1> baz;
>>>>   @Inject
>>>>   private Baz<List<T2>> t2BazList;
>>>> }
>>>>
>>>> @RequestScoped
>>>> public class Foo extends Bar<String, Qux> {
>>>> }
>>>>
>>>> public class Producer {
>>>>   @Produces
>>>>   @Amazing
>>>>   public String produceString() {
>>>>     return "ok";
>>>>   }
>>>>
>>>>   @Produces
>>>>   public String[] produceStringArray() {
>>>>     return new String[0];
>>>>   }
>>>>
>>>>   @Produces
>>>>   public Baz<Baz<Qux>> produceBazBazQux() {
>>>>     return new Baz();
>>>>   }
>>>> }
>>>>
>>>> The class Bar has some more injection points, but that does not matter.
>>>> Due to the TCK this deployment should work, but I don't know how.
>>>> Question: Is Baz a Bean (I suppose so) and may it be injected into
>>>> Bean Foo, more precisely into the second injection point of class Bar?
>>>> - If yes, it also should be injected into the first injection
>>>> point, right? This would lead to an AmbiguousResolutionException since
>>>> Qux may also be injected into the first injection point.
>>>> - If no, the deployment should fail with a
>>>> UnsatisfiedResolutionException since there is no Bean that can be
>>>> injected into that injection point.
>>>>
>>>> Is this a bug in the TCK and if not, how is this supposed to work?
>>>>
>>>> Cheers,
>>>> Arne
>>>>
>>>>
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>>>
>>>
>>>
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