[jira] [Commented] (SLING-3718) Sling Models: Add self Injector for supporting chains of object injecting dependencies from a common source

["Justin Edelson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SLING-3718?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14048342#comment-14048342 ] 

Justin Edelson commented on SLING-3718:
---------------------------------------

Yes, these are both examples of what am concerned about. Neither of these are illegal class design.

> Sling Models: Add self Injector for supporting chains of object injecting dependencies from a common source
> -----------------------------------------------------------------------------------------------------------
>
>                 Key: SLING-3718
>                 URL: https://issues.apache.org/jira/browse/SLING-3718
>             Project: Sling
>          Issue Type: Improvement
>          Components: Extensions
>            Reporter: Stefan Seifert
>            Priority: Minor
>
> as discussed in my post on the sling mailing list
> http://mail-archives.apache.org/mod_mbox/sling-dev/201406.mbox/%3C580AFA6C6DAB8A4196956DA5EE17C8CA8F7619E558@feanor.pro-vision.de%3E
> it would be very helpful to have a "self-adapting" injector to support chains of objects (e.g. controller classes depending on business classes) that all can adapt themselves from a common source, e.g. a SlingHttpServletRequest or a ResourceResolver.
> souch an injector can be simple like this:
> {code:java}
> @Component
> @Service
> @Property(name = Constants.SERVICE_RANKING, intValue = 50)
> public class SelfAdaptInjector implements Injector {
>   public String getName() {
>     return "selfadapt";
>   }
>   public Object getValue(Object pAdaptable, String pName, Type pType, AnnotatedElement pElement,
> DisposalCallbackRegistry pCallbackRegistry) {
>     if (!(pType instanceof Class)) {
>       return null;
>     }
>     if (!(pAdaptable instanceof Adaptable)) {
>       return null;
>     }
>     return ((Adaptable)pAdaptable).adaptTo((Class<?>)pType);
>   }
> }
> {code}
> comment from Justin on this in the mailing list:
> {quote}
> The self injector is interesting. I held off on that initially because
> it seems too easy to create a circular injection. Any thoughts on how
> that can be avoided?
> \[...\]
> Regards,
> Justin
> {quote}



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