[cdi-dev] [JBoss JIRA] (CDI-576) Provide an API to say a bean depends on another instance

Romain Manni-Bucau (JIRA) issues at jboss.org
Fri Dec 18 13:45:01 EST 2015

Romain Manni-Bucau created CDI-576:

             Summary: Provide an API to say a bean depends on another instance
                 Key: CDI-576
                 URL: https://issues.jboss.org/browse/CDI-576
             Project: CDI Specification Issues
          Issue Type: Epic
            Reporter: Romain Manni-Bucau

Sometimes you want to initialize a bean before another bean. This is typically the case of @DependsOn with CDI but it can be more vicious and through several layers.

If A depends on B which depends on C then we can desire to initialize C before A but if A, B and C are normal scoped then it will not happen before C is touched before touching A.

We can't guarantee we can find the dependency and it is not desirable to hardcode it sometimes (test mock shouldnt go in "main" code typically). That's why having an event (guess it will belongs to extensions) allowing to require this kind of eager initialization can be nice.

we would get something like

event.dependencyOn(bean1, bean2);

and it would be fired before after validation event.

The runtime behavior will be to create bean2 before bean1 (I have no issue reversing params/renaming the method). Only trick will be for not normal scoped beans where we can need to reuse the same instance but it sounds feasible in term of implementation since we'll be in the "create" stack anyway.

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