[cdi-dev] [JBoss JIRA] (CDI-723) Obtaining 'original' type/instance of alternatives
Matej Novotny created CDI-723:
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Summary: Obtaining 'original' type/instance of alternatives
Key: CDI-723
URL: https://issues.jboss.org/browse/CDI-723
Project: CDI Specification Issues
Issue Type: Feature Request
Affects Versions: 2.0 .Final
Reporter: Matej Novotny
This issue is based on [CDI mailing list
duscussion|http://lists.jboss.org/pipermail/cdi-dev/2018-February/010088....].
The request is, given that there is one (or more) alternative(s) in place, to be able to
obtain an instance of the original bean.
E.g. given that I have:
{code}
public interface FooFace{...} // interface
@ApplicationScoped
public class FooImpl{...} // 'original' impl
@ApplicationScoped
@Alternative
@Priority(1)
public class AltFooImpl{...} // alternative impl
{code}
I want to be able to put my hands on {{FooImpl}} instance.
The use case is to be able to obtain certain data from it, or simply build on top of it
and it concerns both, producers and "classic" beans defined as classes and
overriden via alternatives.
As for implementation, this could be done on the {{Instance}} level, given an additional
structure is added. What would be needed is a way to say that you want to resolve all
beans of given type, but without throwing away disabled alternatives. Then you want to
allow user to browse through those beans (with access to metadata - {{Bean<?>}}.
With that in place, user could then browse all the beans and choose which one to
instantiate.
Following is an idea of how this could be done using structures have in Weld:
For instance, in Weld this would be possible using our internal structure, called
{{Handler}}, which allows to browse bean metadata. From {{WeldInstance}} (enriched version
of {{Instance}}), you can call {{getHandler()}} to obtain the object. With this in place
we could pretty easily allows user to get all the beans with given type, inspect them, and
then instantiate whichever is needed.
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