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From "Howard M. Lewis Ship (JIRA)" <j...@apache.org>
Subject [jira] [Created] (TAP5-1510) The @Advise annotation limits advise to just a specific interface type
Date Wed, 20 Apr 2011 00:16:06 GMT
The @Advise annotation limits advise to just a specific interface type
----------------------------------------------------------------------

                 Key: TAP5-1510
                 URL: https://issues.apache.org/jira/browse/TAP5-1510
             Project: Tapestry 5
          Issue Type: Bug
          Components: tapestry-ioc
    Affects Versions: 5.2.5, 5.3.0
            Reporter: Howard M. Lewis Ship


@Advise requires that you specify a service interface (there's no default value).  This is
much more limiting than the advise method naming prefix, which will match all services (subject
to the use of @Match), without regard to service interface.

Further, inside ModuleImpl:


    private boolean markerMatched(ServiceDef serviceDef, Markable markable)
    {
        if (!serviceDef.getServiceInterface().equals(markable.getServiceInterface()))
            return false;;


here, the Markable is the AdvisorDef2 instance generated from the @Advise annotation.  This
is an exact comparison; I believe this should be:

  if (! markable.getServiceInterface().isAssignableFrom(serviceDef.getServiceInterface()))
return false;

That, combined with a default of Object.class for @Advisor.serviceInterface would do the trick
... the @Advise.serviceInterface acts as an umbrella over any services' service interface.

..... ok, did more research and more stepping with the debugger.  The above should be fixed,
but it's only the second case of matching, the primary match should be based on the @Match
annotation ... but that's broken too:


Frrom DefaultModuleDefImpl:

    private <T extends Annotation> String[] extractPatterns(T annotation, String id,
Method method)
    {
        if(annotation != null)
            return new String[]{};
       
        Match match = method.getAnnotation(Match.class);

        if (match == null)
            return new String[]
            { id };

        return match.value();
    }

Here, the annotation is the @Advise annotation; I don't get why it returns empty string array;
we should still see if there's a @Match annotation. Looking at the code, I can't see any reason
why we would return that empty string array, the presense of the @Advise annotation (or for
a decorator method, the @Decorate annotation) has no purpose I can figure out.


In my situation, my advise method was not invoked because
a) Primary check (by service id) failed, because the @Match annotation was ignored
b) Secondary check (by service type and marker annotations) failed, because of inexact match
on service interface

So, the end result is the @Advise is only useful to advise a specific service interface, which
is the opposite of what method advice is about ... it's supposed to match against a swath
of services, adapting the advise to whatever methods are present in those services.

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