Re: [aspectj-users] Semantics Question (What are the correct names for t

["Andy Clement" <andrew.clement@xxxxxxxxx>]

Join points occur as a program executes. Fields are set, methods are called, exceptions are handled - these are all join points.  You define a pointcut to choose which join points you are interested in.  A pointcut:

pointcut p(): set(int *);

will match upon all the join points where a field of type 'int' is being set.

A pointcut is a language construct in an AspectJ program.  Named pointcuts can be used

pointcut p(): set(int *);

before(): p() {
}

OR you can just use them inline in the advice signature:

before(): set(int *) {}

But you gain something in being able to name them - you can use a name that will mean something in 6months time when you look back at the code and wonder what on earth your complex pointcut was trying to match.  Named pointcuts are also used in aspect libraries:

abstract aspect Tracing {
  abstract pointcut scope();

  before(): scope() { System.out.println("Entering "+thisJoinPoint);}
  after(): scope() { System.out.println("Exiting"+thisJoinPoint);}

}

aspect MyApplicationTracing extends Tracing {
  pointcut scope(): within(com.mycode..*);
}

Andy.

2008/12/10 Jason Weinstein <Jason.Weinstein@xxxxxxx>

Thanks Andy.

So where does the joinpoint fit into the picture below?? Is a joinpoint the runtime location of a pointcut? Kind of like an instance of a class (joinpoint) vs. a class definition (pointcut)??

Andy Clement wrote:

Hi,

2008/12/9 Jason Weinstein <Jason.Weinstein@xxxxxxx>:
  

What are the correct names for these pieces

Example

  public pointcut NormalizedMessage_new() :
      call(NormalizedMessage+.new(..));

  Object around() :
      NormalizedMessage_new() {
      logEntering(thisJoinPoint);
      return proceed();
  }

1. (pointcut - this one i can do)
  public pointcut NormalizedMessage_new() :

    

It is a named pointcut.  it has a pretty poor name though...  I'd
prefer something like
constructionOfNormalizedMessage() perhaps, something more readable.
The ability to name the pointcuts is a powerful feature that helps you
understand what the pointcut is trying to achieve - don't just
translate the pointcut body directly into a name.

  

2.
      call(NormalizedMessage+.new(..));
    

This is a kinded pointcut designator, the one named 'call' - which
selects call join points.  Typically you would include a scoped
pointcut designator, like within() or withincode() to limit where you
are looking for the call join points, but it is not always required.
You may also include some of the binding pointcut designators to
expose context from the join point (you might use args() to exposed
the arguments at the call).

  

3.
  Object around() :
      NormalizedMessage_new() {
      logEntering(thisJoinPoint);
      return proceed();
  }
    

This is around advice.  If you had a better pointcut name the
declaration may read a little more friendly:

Object around(): constructionOfNormalizedMessage() {

"around constructionOfNormalizedMessage"

  

4a.
  Object around() : NormalizedMessage_new()
    

advice declaration/signature.

  

4b.
      logEntering(thisJoinPoint);
      return proceed();
  }
    

advice body.  This around advice body uses a proceed to invoke the
originally matched join point.
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