On Sep 3, 2008, at 10:11 PM, Andy Clement wrote:
In the first case, the generated compare method is a generics bridge
method - which merely acts as a bridge from the (Object,Object)
variant to your (String,String). If you look at the bytecode for
it, you will see it calls the other compare method.
AspectJ does not advise bridge methods, because they just delegate
to the 'real' method. If we did then in this case your advice would
run twice if you called the Object,Object version.
In your second case you provided your own compare(Object,Object)
method and so it was advised.
Thanks Andy for the rapid answer.
If I understood well, AspectJ does not advise bridge method as
optimization...
The problem is that we need to advice all methods (from third
party compiled code)... which is important for context sensitive
applications. Currently we have 'lost slots' because of the non
advised bridge methods, which are very hard to debug :-(
I'm not sure if enabling advise of bridge methods could benefit
other users.... but it would be helpful to have such a feature.
Cheers,
Alex
cheers,
Andy.
2008/9/3 Alex Villazon <[EMAIL PROTECTED]>
Dear all,
I have a problem with the following aspect which can advice
methods, depending on how it's compiled...
public class A implements java.util.Comparator <String> {
public int compare(String a, String b) {
return 0;
}
}
javac generated a compare(Object, Object) method corresponding to
public int compare(Object a, Object b) {
return compare((String)a, (String)b);
}
When weaving A.java with the following aspect, only the
compare(String, String) method is adviced...
public aspect Foo {
before() : execution(* *(..)) && !within(Foo) {}
}
javac A.java
jar cvf a.jar A.class
ajc -showWeaveInfo -inpath a.jar -outjar woven.jar Foo.aj
Join point 'method-execution(int A.compare(java.lang.String,
java.lang.String))' in Type 'A' (A.java:3) advised by before advice
from 'Foo' (Foo.aj:2)
Now, if I add the compare(Object, Object) manually, the Foo aspect
advice both compare(String, String) and compare(Object, Object)
methods!!!!
public class A implements java.util.Comparator /*<String> */ {
public int compare(String a, String b) {
return 0;
}
public int compare(Object a, Object b) {
return compare((String)a, (String)b);
}
}
javac A.java
jar cvf a.jar A.class
ajc -showWeaveInfo -inpath a.jar -outjar woven.jar Foo.aj
Join point 'method-execution(int A.compare(java.lang.String,
java.lang.String))' in Type 'A' (A.java:3) advised by before advice
from 'Foo' (Foo.aj:2)
Join point 'method-execution(int A.compare(java.lang.Object,
java.lang.Object))' in Type 'A' (A.java:6) advised by before advice
from 'Foo' (Foo.aj:2)
Curiously, the bytecode for compare(Object, Object) is strictly the
same.. in both cases..
public int compare(java.lang.Object, java.lang.Object);
Signature: (Ljava/lang/Object;Ljava/lang/Object;)I
Code:
Stack=3, Locals=3, Args_size=3
0: aload_0
1: aload_1
2: checkcast #2; //class java/lang/String
5: aload_2
6: checkcast #2; //class java/lang/String
9: invokevirtual #3; //Method compare:(Ljava/lang/String;Ljava/
lang/String;)I
12: ireturn
LineNumberTable:
line 1: 0
Is this a bug of ajc? I tested it with 1.6.1 and 1.6.2
(development version)
Thanks a lot,
Alex
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