[cdi-dev] [JBoss JIRA] (CDI-227) BeanManager#resolve() is underspecified for corner cases

[Martin Kouba (JIRA)]

    [ https://issues.jboss.org/browse/CDI-227?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12724350#comment-12724350 ] 

Martin Kouba commented on CDI-227:
----------------------------------

I don't get the last bullet in *"11.3.8. Resolving an ambiguous dependency"*:
{quote}
* no bean is available for injection in the module (as defined in Section 5.1, “Modularity”)
{quote}

I think {{BeanManager.resolve()}} should only apply ambiguous dependency resolution rules. So the only possibilities are:
# null is passed => return null
# no beans are passed (empty list) => return null
# non-empty set of beans is passed:
## set.size() == 1 => the bean is returned
## set.size() > 1 ...an ambiguous dependency exists:
### is not resolvable => AmbiguousResolutionException is thrown
### is resolvable => the bean is returned

However there might be some corner case I don't see...
                
> BeanManager#resolve() is underspecified for corner cases
> --------------------------------------------------------
>
>                 Key: CDI-227
>                 URL: https://issues.jboss.org/browse/CDI-227
>             Project: CDI Specification Issues
>          Issue Type: Bug
>          Components: Java SE Integration, Packaging and Deployment
>    Affects Versions: 1.0, 1.1.EDR
>            Reporter: Guy Veraghtert
>            Assignee: Pete Muir
>              Labels: patch
>             Fix For: 1.1.PRD
>
>
> The CDI api's are mainly used to develop (portable) extensions. In practice, we see that those so called _portable_ extensions are not portable at all due to underspecified api's.
> For example BeanManager.resolve(set) doesn't specify how to deal with an empty set or null. This leads to incompatible implementations and unportable extensions. See for example https://issues.apache.org/jira/browse/OWB-625 (Unfortunately Websphere 8 includes openwebbeans < 1.1.3, making Seam3 not out-of-the-box usable). Currently most implementations (weld, owb and candi) return null for an empty set. OWB returns null when null is passed, others will throw an exception.
> To create extensions that are truly portable, we should specify all corner cases (what about BeanManager.getBean((String)null)?). In theory  developers should not depend on undefined behavior, but in practice we all do (Seam3 is full of examples).
> Ideally, we should go over the complete public API and specify what should happen with these corner cases: null-values, empty collections, ...
> Just adding that an IllegalArgumentException should be thrown in case of null for example would suffice.
> These things are very easy to incorporate in the TCK and would contribute a lot to the success of portable extensions

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