Re: [aspectj-users] static cross cutting and method call introduction

[Ramnivas Laddad <ramnivas@xxxxxxxxx>]

How about the following aspect?

/* privileged */ aspect TestAspect {
    pointcut contentHandler( ) : 
        execution(* org.xml.sax.ContentHandler.*(..));

    Object around(ContentHandler ch): contentHandler() && this(ch) {
        return proceed(ch.anotherContentHandler);
    }
}

You will need to mark the aspect as privileged if
anotherContentHandler is not accessible from the aspect
(and there is no getter method to access that field, either).

-Ramnivas

===
Ramnivas Laddad, 
Author, AspectJ in Action 
http://www.manning.com/laddad
http://www.amazon.com/exec/obidos/ASIN/1930110936

Check out my aspect-oriented refactoring articles:
http://tinyurl.com/yqm96
http://tinyurl.com/288nn


--- Jakob Praher <jpraher@xxxxxxxx> wrote:
> hi all,
> 
> today I looked at the execution( ) pointcuts and was asking myself,
> if
> it would be possible (with aspectj-1.2) to introduce a method
> redirection, without using java reflection.
> 
> It would certainly work, since the type information is known at
> compile
> time.
> 
> like for instance:
> 
> aspect TestAspect {
> 
> pointcut contentHandler( ): execution( *
> org.xml.sax.ContentHandler.*(..));
> 
> 
> around( ): contentHandler()  {
> 	
>  // assert : thisJoinPoint.getSignature( ).getKind( ) ==
> Signature.METHOD_EXECUTION;
> 
>  MethodSignature ms = (MethodSignature) thisJoinPoint(
> ).getSignature(
> ); 
>   
>  Field f = thisJoinPoint.getThis( ).getClass( ).getField(
> "anotherContentHandler" );
>  
>  ContentHandler anotherContentHandler = (ContentHanlder ) f.get(
> thisJoinPoint.getThis( ) );
> 
>  Method m = anotherContentHandler.getClass( ).getMethod( ms.getName(
> ),
> ms.getParameterTypes( ) );
>  
>  return m.invoke( anotherContentHandler, thisJoinPoint.getArgs( ) );
>  
> } // end arround advice
> 
> } // end aspect
> 
> Here I have to use java.lang.reflect.Method to get to the target
> Method.
> But since you are doing bytecode manipulation anyway adding an entry
> to
> the constant pool and calling 
> 
> invokevirtual #newId
> 
> would not be that hard, and would certainly be faster than using
> java.lang.reflect.Method.invoke.
> 
> I don't know whether thats already possible or why it is not
> possible,
> but perhaps you can give me some info.
>  
> And another question: Is it possible to circumvent the static
> redirection which apparently the static crosscutting introduces.
> 
> I noticed (through javap) that the body of a static croscutted method
> is
> a static method implemented in the aspects class, and there is only a
> stub implementation on the class which got crosscutted.
> 
> I would like to access for instance some fields of the class which
> are
> not public. (Ok putting both in the same package would reduce the
> access
> level to package private).
> 
> thanks 
> -- Jakob
> 
> 
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