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

["Stefan Seifert (JIRA)" <ji...@apache.org>]

Stefan Seifert created SLING-3718:
-------------------------------------

             Summary: 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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