[jbossseam-issues] [JBoss JIRA] Commented: (JBSEAM-3362) Detect cyclic dependencies and throw exception

[Pete Muir (JIRA)]

    [ https://jira.jboss.org/jira/browse/JBSEAM-3362?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12427672#action_12427672 ] 

Pete Muir commented on JBSEAM-3362:
-----------------------------------

> Say Foo has an @In(required=false) attribute called somethingProvidedByBar.
> When someMethod() is invoked on Foo, and trying to satisfy the injection of bar
> results in Bar calling Foo.someOtherMethod(), then we should bail on this injection
> attempt, and let somethingProvidedByBar be null for the invocation of someMethod(). 

Exactly. However I too can't immediately see a good way to implement this, apart from reworking the BijectionInterceptor to allow cyclic dependencies again.

How about we get (1) fixed, and then release like this in CR and see if we get many complaints from users.

> Detect cyclic dependencies and throw exception
> ----------------------------------------------
>
>                 Key: JBSEAM-3362
>                 URL: https://jira.jboss.org/jira/browse/JBSEAM-3362
>             Project: Seam
>          Issue Type: Feature Request
>          Components: Core
>    Affects Versions: 2.0.3.CR1, 2.1.0.BETA1
>            Reporter: Matt Drees
>            Assignee: Matt Drees
>            Priority: Minor
>             Fix For: 2.0.3.CR2, 2.1.0.CR1
>
>
> Imagine a scenario like this.  Some client calls someMethod() on a component called Foo.  BijectionInterceptor tries to inject Foo's @in attributes, one of which requires calling a factory method on Bar.  Bar's factory method in turn calls Foo.someOtherMethod().  Foo is not in a state where it can support method calls, because it is in the process of injecting dependencies, so this sort of cyclic dependency should not be allowed.  Seam should throw an exception in this case.
> BijectionInterceptor used to be coded such that someOtherMethod() would run without any complaints, and any @In attributes may or may not be null, depending on which fields were injected first.  Recent changes to BijectionInterceptor (for JBSEAM-3295) have changed this behavior, and now an finite loop results.  Neither of these behaviors is desirable.

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