[cdi-dev] [JBoss JIRA] (CDI-712) Clarify whether is should be possible to "override" built-in Instance/Provider

[Martin Kouba (JIRA)]

    [ https://issues.jboss.org/browse/CDI-712?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13445688#comment-13445688 ] 

Martin Kouba commented on CDI-712:
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bq. A Long Bean would also work but then it would go through the whole CDI stack for EACH and every invocation!
Not a big deal.

bq. Also the spec does NOT state that one cannot provide an Alternative for built-in beans.
Agreed.

bq. Note that it is also important to allow custom implementations of javax.inject.Provider as the Container would otherwise not be able to implement JSR-330 afaict.
I don't understand even a little.

bq. This is just a standard bean...
It's not standard in the way that it must satisfy all {{Instance<X>}} or {{Provider<X>}} for any legal bean type {{X}} and qualifiers are also handled specially. In other words, the built-in bean must be treated in a special way.


> Clarify whether is should be possible to "override" built-in Instance/Provider
> ------------------------------------------------------------------------------
>
>                 Key: CDI-712
>                 URL: https://issues.jboss.org/browse/CDI-712
>             Project: CDI Specification Issues
>          Issue Type: Clarification
>            Reporter: Martin Kouba
>
> In theory, an extension could register an alternative custom bean to override the built-in Instance/Provider bean for injection points such as {{@Inject Provider<String>}}. 
> It is not forbidden at the moment. The spec only states that there must be a built-in bean eligible for any injection point with Instance/Provider required type and any qualifier. See also https://docs.jboss.org/cdi/spec/2.0/cdi-spec.html#builtin_instance.
> It seems to be a powerful feature. On the other hand, it might be a source of confusion. Take for example this injection point:
> {code:java}
> @Inject
> @MyQualifier
> Instance<String> instance;
> {code}
> The qualifier is now considered when calling {{instance.get()}} and NOT when resolving the injection point.
> Note that the spec already allows to decorate built-in beans.



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