[cdi-dev] [JBoss JIRA] (CDI-331) Instance.iterator() shouldn't include non-alternatives that haven't been replaced

[Jozef Hartinger (JIRA)]

    [ https://issues.jboss.org/browse/CDI-331?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12759125#comment-12759125 ] 

Jozef Hartinger commented on CDI-331:
-------------------------------------

This code snippet illustrates the problem:

{code}
Instance<Foo> = ...

if (!instance.isAmbiguous()) {
    instance.get(); // do something with it
} else {
    // choose the appropriate instance
}
{code}

The intuitive code snippet above is wrong. You cannot effectively use isAmbiguous() to reflect whether there are multiple matching instances.

For example if there were two matching @Alternative beans, each with a different priority, isAmbiguous() would still return true even though instance.get() is capable of returning the appropriate instance (the alternative with the highest priority).
                
> Instance.iterator() shouldn't include non-alternatives that haven't been replaced
> ---------------------------------------------------------------------------------
>
>                 Key: CDI-331
>                 URL: https://issues.jboss.org/browse/CDI-331
>             Project: CDI Specification Issues
>          Issue Type: Feature Request
>          Components: Resolution
>    Affects Versions: 1.1.PRD
>            Reporter: Jozef Hartinger
>            Assignee: Pete Muir
>             Fix For: TBD
>
>
> The specification currently says that:
> {quote}
> The iterator() method must:
> • Identify the set of beans that have the required type and required qualifiers and are eligible for injection into the class into
> which the parent Instance was injected, according to the rules of typesafe resolution, as defined in Section 5.2.1.
> {quote}
> The ambiguity resolution algorithm as defined in 5.2.2 should be applied.
> This is explicitly required for get() but is not required for iterator(). This causes the following inconsistency:
> Assume two classes Foo and Bar which both implement common interface Common. Bar is an enabled alternative.
> Assume further the following 
> {noformat}
> @Inject @Any Instance<Common> instance
> {noformat}
> injection point.
> It is clear that instance.get() returns Bar.
> It is however not clear whether instance.iterator() iterates over:
> a) Bar
> b) Foo, Bar
> and whether instance.isAmbiguous() returns:
> a) true
> b) false

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