Re: [aspectj-users] About AspectJ pointcut

[Matthew Webster <matthew_webster@xxxxxxxxxx>]

Kawtip,

Your pointcut "execution(public
void Level2.*());" matches all
methods defined on Level2 (including any it inherits). Level3.printA()
is a method defined on Level2 but overridden in Level3. Changing the pointcut
to "execution(public void Level2+.*());"
 would include all methods defined (not overridden) in subclasses
of Level2. If you added another method in Level3 say "public void
printB()" then that would be matched by the new pointcut.

The Level2 class itself is not advised
because it does not implement any methods that are matched by the pointcut.
To advise instances of Level2 you would need to change your pointcut to
"execution(public
* TestAccessModifiers.*())"
giving these results:

execution(void TestAccessModifiers.printA())
A
execution(void Level3.printA())
Level3 protected
execution(void Level3.printA())
Level3 protected

Cheers

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/

Kawtip Nippon <kawtip@xxxxxxxxx>
Sent by: aspectj-users-bounces@xxxxxxxxxxx

12/08/2006 16:54

Please respond to
aspectj-users@xxxxxxxxxxx

To	aspectj-users@xxxxxxxxxxx
cc
Subject	[aspectj-users] About AspectJ pointcut

Dear all, 
 
     I'd like to ask about AspectJ pointcut. From this quotation
from aspectj tutorials... 
--------------------------------------------------------
When matching method-execution join points, if the execution pointcut method
signature specifies a declaring type, the pointcut will only match methods
declared in that type, or methods that override methods declared in or
inherited by that type. So the pointcut 
  execution(public void Middle.*())  
picks out all method executions for public methods returning void and having
no arguments that are either declared in, or inherited by, Middle, even
if those methods are overridden in a subclass of Middle. So the pointcut
would pick out the method-execution join point for Sub.m() in this code:
  class Super {      protected void m() { ... }  
 }    class Middle extends
 Super {    }    class Sub extends Middle {  
   public void m() { ... }    }
--------------------------------
   I try to write some code to test. This is the code...
--------------------------------------------------------
class TestAccessModifiers {
 public void printA(){  System.out.println("A"); }}class
Level2 extends TestAccessModifiers{ }class Level3 extends Level2{ public
void printA(){  System.out.println("Level3 protected");
} public static void main(String[] args){  Level2 l2 = new Level2();
 l2.printA();  Level3 l3 = new Level3();  l3.printA();  Level2
l22 = new Level3();  l22.printA(); }
}
aspect CallMethods {
 pointcut exeM(): execution(public void Level2.*());
 before(): exeM(){
  System.out.println(thisJoinPoint);
 }
 
}
--------------------------------------------------------
     and this is the result after i run the class (using ajdt
with eclipse)
--------------------------------------------------------
A
execution(void p8.Level3.printA())
Level3 protected
execution(void p8.Level3.printA())
Level3 protected
--------------------------------------------------------
     I questioned that why the poincut can capture Level3.printA().
I thought that it can't capture this JoinPoint and it can capture this
JoinPoint if the pointcut specify that execution(public void Level2+.*())
instead (+ should make the pointcut cover methods in Level3 class).
     And I wonder that why the pointcut can't capture a joinpoint
l2.printA().
 
     Thank you very much in advance for you all,
Kawtip

 

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