Re: [aspectj-dev] Constructor Join Point and Super() constructor

["Wes Isberg" <wes@xxxxxxxxxxxxxx>]

> what exactly I want is to call the
> constructor of Superclass  class before the constuctor
> of Tester class. 

As I said, what you're asking specifically is not possible
because of the special semantics of super() in a
constructor.

When you are interposing a new parent, you can use after
advice to do initialization in the parent after the child
instance has initialized:

  after() returning (SuperClass me) : 
     call((!SuperClass && SuperClass+).new(..)) {
     me.init("hello");
  }

That means using a method to do some superclass
initialization after the subclass constructor has run.

You can't do this before the subclass constructor runs
because there is no target object for a constructor
execution.

Hope this helps -
Wes

On Thu, 1 Sep 2005 12:44:02 +0100 (BST)
 nathar shah <shah123khan@xxxxxxxxx> wrote:
> Erm..There is a problem with your suggested approach.
> 
> Let put the scenario clearer..
> I am the programmer for a class named Superclass
> and I need to weave the bytecode Testear class writen
> by someone that i dont know. 
> 
> I am modifying the Tester class
> relationship(structure) through :-
> >  declare parents: Tester extends Superclass;
> This construct is part of my Test aspect construct
> shown earlier. Assuming that the programmer does not
> have access to the source code and he/she can only
> modify (or weave) the bytecode of Tester class, it is
> not possible for the programmer to know constructors
> of Tester class. 
> 
> It is also not possible for me to override (by using
> around() advice) the constructors of Tester class
> because it may cause problems as I dont know what
> initialisation they are doing in the constructor. The
> least that i could do is just weave each constructor
> in Tester (I have only shown 1 constructor in my
> previous email, but now assume that there are many
> constructors in Tester class) with super(*,*) keyword
> so that a specific constructor of Superclass class can
> be invoked
> 
> Your approach only allows another constructor of
> Tester  class to be called instead the default Tester
> constructor. But, what exactly I want is to call the
> constructor of Superclass  class before the constuctor
> of Tester class. 
> 
> How would this be possible? 
> 
> Regards,
> Shah
> 
> 
> 
> --- Wes Isberg <wes@xxxxxxxxxxxxxx> wrote:
> 
> > aack!
> > 
> > >  void around(): cons(){
> > >    super(a, b);
> > 
> > super(..) should never be available in advice.
> > That I think is a compiler bug.
> > 
> > wrt calling super, does it work to declare the
> > constructor?
> > 
> >    Target.new() {
> >      super("hello");
> >      ...
> >    }
> > 
> > (If the default constructor is already declared,
> > then you
> > can't do that.)
> > 
> > Another approach is to replace the calls:
> > 
> >   Target around() : call(Target.new()) {
> >      return new Target("hello");
> >   }
> > 
> > You might combine this with the inter-type
> > declaration of
> > the constructor.
> > 
> > Since super(..) is a special form in Java, that's
> > pretty
> > much all you can do in AspectJ.
> > 
> > Wes
> > 
> > On Thu, 1 Sep 2005 00:33:37 +0100 (BST)
> >  nathar shah <shah123khan@xxxxxxxxx> wrote:
> > > Hi,
> > > 
> > > I am looking at ways of developing an aspect which
> > > will call super() in the constructor so that its
> > super
> > > constructor can be called. For example if I have
> > class
> > > such as 
> > > 
> > > public class Tester{
> > >    public Tester(){
> > >    }
> > > }
> > > 
> > > Currently implicit super() constructor is called
> > > automatically. But I want an aspect which will
> > call
> > > explicit super() constructor with some
> > arguments.The
> > > class structure of Tester will be modified using
> > > declare parents. I have developed an aspect such
> > as
> > > follows but facing problem when it is weaved
> > saying
> > > "super constructor call must be the first
> > statement in
> > > the constructor"
> > > 
> > > aspect Test{
> > >  declare parents: Tester extends Superclass;
> > > 
> > >  ClassA a = new ClassA();
> > >  ClassB b = new ClassB();
> > >  
> > >  pointcut cons(): preinitialization(Tester.new());
> > > 
> > >  void around(): cons(){
> > >    super(a, b);
> > >    proceed();
> > >  }
> > > }
> > > 
> > > Note: I need the aspect to modify the Tester class
> > > structurally by extending Superclass class. Thus,
> > I
> > > need to call Super() constructor with some
> > arguments
> > > before the constructor of Tester is executed. 
> > > 
> > > This is a simple simulation of the problem I am
> > facing
> > > in my application development. Could anyone there
> > help
> > > me?
> > > 
> > > 
> > > 
> > > 
> > > 		
> > >
> >
>
___________________________________________________________
> > > 
> > > How much free photo storage do you get? Store your
> > > holiday 
> > > snaps for FREE with Yahoo! Photos
> > > http://uk.photos.yahoo.com
> > > _______________________________________________
> > > aspectj-dev mailing list
> > > aspectj-dev@xxxxxxxxxxx
> > >
> > https://dev.eclipse.org/mailman/listinfo/aspectj-dev
> > 
> > _______________________________________________
> > aspectj-dev mailing list
> > aspectj-dev@xxxxxxxxxxx
> > https://dev.eclipse.org/mailman/listinfo/aspectj-dev
> > 
> 
> 
> 
> 
> 
> 		
>
___________________________________________________________
> 
> To help you stay safe and secure online, we've developed
> the all new Yahoo! Security Centre.
> http://uk.security.yahoo.com
> _______________________________________________
> aspectj-dev mailing list
> aspectj-dev@xxxxxxxxxxx
> https://dev.eclipse.org/mailman/listinfo/aspectj-dev