Re: [aspectj-users] why the !within! in the aspect

[Matthew Webster <matthew_webster@xxxxxxxxxx>]

Nadia,

This is because you are still advising the constructor execution for Lolo
which can be omitted using:

      && !execution(new(..))

however you then fall into the trap of recursion: there is the execution of
the before advice itself as well as the "System.out..." statement which has
at least 4 join points. You should try using AJDT and the Outline or Cross
Reference view to see what affect you aspect is having. An alternative is
-XshowWeaveInfo option in AspectJ 1.2.1.

Using an aspect to advise itself is _very_ problematic and usually
undesirable. For that reason !within(Aspect) is a popular idiom. More
importantly advice is typically used with a particular kind of join point
e.g. method execution a practice which avoids this sort of problem.

Matthew Webster
AOSD Project
Java Technology Centre, MP146
IBM Hursley Park, Winchester,  SO21 2JN, England
Telephone: +44 196 2816139 (external) 246139 (internal)
Email: Matthew Webster/UK/IBM @ IBMGB, matthew_webster@xxxxxxxxxx
http://w3.hursley.ibm.com/~websterm/

"Nadia Guerroumi" <n_guerro@xxxxxxxxxxxxxxxx>@eclipse.org on 08/04/2005
14:22:00

Please respond to aspectj-users@xxxxxxxxxxx

Sent by:    aspectj-users-bounces@xxxxxxxxxxx


To:    <aspectj-users@xxxxxxxxxxx>
cc:
Subject:    [aspectj-users] why the !within! in the aspect


According to an answer that I had in this forum:

For #2, your before advice in Lolo was executing on staticinitialization of
the Lolo aspect, which failed because the aspect wasn’t yet initialized.
You already figured out the way to avoid the problem J



I was expecting that the following aspect will work but it still gives the
error NoAspectBoundException: Lolo

Why???? Why I must put the !within(Lolo)


aspect Lolo

{


pointcut p2(): !staticinitialization(*)&& ! initialization
(*.new(..))&&!preinitialization(*.new(..));

before(): p2() {

System.out.println(">>Before the join point:"+thisJoinPoint);

}


    class Nadia1 {
 public static Bank b,c;


 public static void main(String[] args) {


 b=new Bank();


 c=new Bank();}}


 class Bank {}


 /****************************************************/


 #2 The aspect was originally


 aspect Lolo


 {


 pointcut p2():if (true);


 before(): p2() {


 System.out.println(">>Before the join point:"+thisJoinPoint);


 }


 }


 Thank you


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