RE: [aspectj-users] why this cflow put counters in aspect itself?

["Wes" <wes@xxxxxxxxxxxxxx>]

In this pointcut

> >     pointcut singleStep(): !within(mypackage..*) && cflow(call(*
> > *(..))) && !execution(* *(..));

there is almost no restriction on the triggering join point, so ajc
can't prove to itself that the cflow will only be true at certain join
points.  So ajc has to set up the program to check whether singleStep()
matches at every join point that might be in the control flow of a method 
execution or call.  This can include join points in the aspect itself;
e.g., advice bodies are in the control flow of the join points they advise.

One of the things that can distinguish implementations of AspectJ is the
degree to which they do static checking to prove that a given cflow will
or won't match.  It's perfectly legal for an implementation to check a 
cflow at every single join point in the program; it's just not efficient.
So it's possible that what you see in the .class files will change with
other AspectJ implementations or even between releases of Eclipse AspectJ.
That's one of the reasons we strongly discourage people from decompiling
the output in order to understand the language semantics.  It's useful
to decompile to track down bugs (e.g., performance issues when using
cflow), but often you get results quicker by playing with the pointcuts
to reduce the join points that might be matched.

Wes

> ------------Original Message------------
> From: "Eric Bodden" <eric.bodden@xxxxxxxxxxxxxx>
> To: aspectj-users@xxxxxxxxxxx
> Date: Thu, Jun-22-2006 3:42 AM
> Subject: RE: [aspectj-users] why this cflow put counters in aspect itself?
>
> Well, by stating !within(mypackage..*) you state that the joinpoint you
> are interested in is not in your aspect package. This however must not
> have any implications on the cflow pointcut and its update-shadow. If
> you want to restrict this, you can change it to:
> 
> cflow(!within(mypackage..*) && call(* *(..)))
> 
> Eric 
> 
> > -----Original Message-----
> > From: aspectj-users-bounces@xxxxxxxxxxx [mailto:aspectj-users-
> > bounces@xxxxxxxxxxx] On Behalf Of Gu Dake
> > Sent: Wednesday, June 21, 2006 8:45 PM
> > To: aspectj-users@xxxxxxxxxxx
> > Subject: [aspectj-users] why this cflow put counters in aspect 
> itself?
> > 
> > package mypackage;
> > 
> > aspect MyAspect {
> > 
> >     pointcut singleStep(): !within(mypackage..*) && cflow(call(*
> > *(..))) && !execution(* *(..));
> > 
> > before(): singleStep() {
> >     System.out.println(thisJoinPointStaticPart);
> > }
> > }
> > 
> > This aspect works fine at runtime.  But when I opened the
> > MyAspect.class in decompile tool, I saw some instrumented
> > ajc$cflowCounter$0.inc() around my println()
> > 
> > 
> 
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