[aspectj-users] Can I do any of these 3 things with aspectJ

["Tarun Sharma" <t_sharma@xxxxxxxxxxxx>]

Hi Guys

I have 3 questions and would be great if you have any comments or
suggestions on these.

Question 1 : If, my requirement is to return a different instance (say
instantiating overloaded constructor) of an object whose default
constructor is called. Can I do that with aspectJ. The limitation is that
I do not want to use call() pointcut, (as this needs the caller's to be
included in weaving though source or binary and I do not have control
over the usages of my framework).

Question 2 : If we use inter-type declaration's for let us say adding
method's to existing classes, what I understood that you cannot define
methods for more than one class in one decleration. For example (1) is
what is possible, IS (2) possible to achieve somehow.? I do not want to
define the same behaviour for every class. I want every class for a
package to get this method added with same behaviour. To achieve this
kind of result, I also tried private interface, but landed in a problem
again which is question 3. 

(1)----   public int Point.getX() { return this.x; }

(2) --    public int com.x.y.*.getX() { return this.x; }

Question 3 : When I tried a private interface, I had a problem again: The
problem is "this" which is explicitly available in the method definition
of the private interface, does seem have limitations. The code I was
trying is below (for simplicity this is the main purpose of code). The
probelm is that, I am using reflection to set instance field
WHICH_IS_PRIVATE and you can only do that from the same class using
"this"(as far as I am aware of), so i thought the below solution might
work.? But it didn't, as the weaving is not done as-is but rather through
references (Obviously I had to de-compile to figure out what's
happening), may be in most cases the waeving works but not in this case
or I am doing something wrong:

	private interface MyInterface {}

	declare parents: com.x.y.MyComponent implements MyInterface ;

	public pointcut populate(java.lang.Object o) : execution(*.new()) && this(o) && within(com.x.y.MyComponent);

	public void MyInterface.setMember(Object memberValue){
		/**
		Using reflection I got the field object of, one of instance field
		defined in MyComponent class.And I try to set this with the memberValue
		argument using the field.set(this,memberValue)
		**/

		Field field = SomeService.getField();								

		    try{
			field.set(this,memberValue);
		    } catch (IllegalArgumentException e) {
		    e.printStackTrace();
		    } catch (IllegalAccessException e) {
		    e.printStackTrace();
		    }
		}

	    }

	after (java.lang.Object o) : populate(o) {	
		MyInterface myInterfaceAwareObject = (MyInterface)o;
		myInterfaceAwareObject.setMember($some_value);
	}

I would really appreciate any comments on these issues or suggestions.

Thanks in advance
Tarun

-- 
  Tarun Sharma
  t_sharma@xxxxxxxxxxxx

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