This() vs Target() aspectj

Question

Can anyone explain the difference between this() and target() pointcuts in aspectj. I tried finding this elsewhere but there doesnt seem to be a clear cut answer. Thank You

Answer 1

At a matching join point, this() is the object you are in, target() is the object you are invoking/referencing. The confusion may arise because in the case of an execution() pointcut matching on a joint point they are the same thing - the object containing the execution join point which matched is the same as the object running the method you are matching on. But in the case of a call() join point they are different. The object making the call is different from the object on which the method is being called.

class A {
  public void m() {
    B b = new B();
    b.n();
  }
}
class B {
  public void n() {
  }
}

For that setup, the pointcut execution(* m(..)) will match on join point A.m() and have a this() of type A and target() of type A (and they will be the same instance of A). However the pointcut call(* n(..)) will match at the call site in method A.m() where it calls n() and at that point this() will be the instance of A making the call whilst target() will be the instance of B that the method is being invoked upon.