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https://issues.jboss.org/browse/CDI-414?page=com.atlassian.jira.plugin.sy...
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Pavel Pscheidl commented on CDI-414:
------------------------------------
I think a good enough solution is to inject a Instance<T> object, where T is a
generic type for the self-injecting bean.
{code:java}
public class Foo {
@Inject
private Instance<Foo> foo;
}
{code}
This works completely fine. Some kind of lazy-injecting proxy would be nice, but
unnecessary. Since dependency injection is an acyclic graph, creating cycle dependecies is
wrong. The code inside the bean should explicitely state (by calling foo.get()) that it
wants to get "yet another" instance from the container.
Some (recursive) algorithms actually might want to use self-injected dependecies. However,
the algorithm explicitely obtains the instance from the container and is in charge of
stopping the recursion.
Support for "self" injection or intercepted self
invocation
-----------------------------------------------------------
Key: CDI-414
URL:
https://issues.jboss.org/browse/CDI-414
Project: CDI Specification Issues
Issue Type: Bug
Components: Resolution
Reporter: arjan tijms
Fix For: 2.0 (discussion)
Many features of CDI and EJB work by means of a proxy that intercepts calls and adds
'aspects'. In Java it's however not possible to decorate the {{this}} pointer,
so methods called on the same bean instance from within a method in the bean do not get
their 'aspects' applied.
This is a well known limitation, but in EJB it's possible to work around this by
injecting a bean into itself. E.g.
{code}
@Stateless
public class Foo {
@EJB
private Foo self;
// ...
}
{code}
Also see
http://adam-bien.com/roller/abien/entry/how_to_self_invoke_ejb
Unfortunately using CDI and {{@Inject}} this doesn't work. Weld for instance fails
the deployment and logs:
{noformat}
WELD-001443 Pseudo scoped bean has circular dependencies.
{noformat}
See also:
http://adam-bien.com/roller/abien/entry/inject_vs_ejb
Although there are workarounds, it would be great if {{@Inject}} in combination with CDI
could support self injection as well.
With that projects migrating from {{@EJB}} to {{@Inject}} can do so more easily and the
capability can be convenient for new projects as well (e.g. calling two separate
{{@Transactional}} methods from a single method without being required to create a new
bean).
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