Jan,
To make the code work on private members you just need to use
getDeclaredField (i.e., it's just a Java reflection API issue). I was thinking
there might be more complexity in using reflection with privates (there usually
is), but in this case it's pretty easy. And, yes, you are likely to want to use
!equals instead of != for most object types..
before(int newVal,
Object container) : set(int ModelClass.*) && args(newVal) &&
this(container) {
Class inClass =
thisJoinPoint.getSignature().getDeclaringType();
String
fieldName = thisJoinPoint.getSignature().getName();
Field
field = inClass.getDeclaredField(fieldName);
int oldVal =
field.getInt(container);
//System.out.println("change
"+oldVal+" to "+newVal);
if
(oldVal != newVal) {
} catch
(Exception e) { e.printStackTrace(); } // handle properly
}
I'll go ahead and
solve the other exercise too. Here is the solution for static fields (use both
to handle all cases). It differs because you can't bind a value for this (there
is none):
before(int newVal) :
set(static int ModelClass.*) &&
args(newVal) {
Class inClass =
thisJoinPoint.getSignature().getDeclaringType();
String
fieldName = thisJoinPoint.getSignature().getName();
Field
field = inClass.getDeclaredField(fieldName);
int oldVal =
field.getInt(null);
//System.out.println("change
"+oldVal+" to "+newVal);
if
(oldVal != newVal) {
} catch
(Exception e) { e.printStackTrace(); } // handle properly
}
Ron Bodkin
Chief Technology Officer
New Aspects of Security
m: (415) 509-2895
------------Original Message-------------
From: "Jan Kerssenfischer" <aspectj@xxxxxxxxxxxxxxxxx>
To: <aspectj-users@xxxxxxxxxxx>
Date: Thu, Jul-31-2003 2:53 PM
Subject: AW: [aspectj-users] How to build a Dirty Flag ?
That´s
a fast answer.
Thank you. To get this code work on private variables I only have to declare
the aspect as privileged, do I. There are different
types of variables to check. I think I can also use an Object and compare it
with the .equals method? I try to find out tomorrow, thank you
again.
Jan
Kerssenfischer
You can use before advice with reflection to achieve your
goal. Here's a simple example where the field is public and is not a static
member. Generalizing to handling private fields and static members is left as
an exercise for the reader :-)
before(int newVal,
Object container) : set(int ModelClass.*) && args(newVal) &&
this(container) {
Class inClass =
thisJoinPoint.getSignature().getDeclaringType();
String
fieldName = thisJoinPoint.getSignature().getName();
Field field = inClass.getField(fieldName);
int
oldVal = field.getInt(container);
//System.out.println("change "+oldVal+" to
"+newVal);
if (oldVal != newVal) {
} catch
(Exception e) { e.printStackTrace(); } // handle
properly
}
Hello,
I
have the following Problem:
If
have some classes representing a data structure. I want to write an aspect,
that adds a dirty flag to a class, that turns true, if one of the values
changed. So far the adding of the Flag is not the problem. My Problem is to
find out, if any of the classvariables is set with a new value. New means in
that case that it is not the old value written again (what my Gui does). To
get the new Value is no problem with a combination of set und args. My
Problem is how to find out the previous value of the variable witch is
written. Target returns the target instance and not the Variable. Are there
any solutions to this problem?
Best
regards,
Jan
Kerssenfischer
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