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

[nathar shah <shah123khan@xxxxxxxxx>]

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?
> > 
> > 
> > 
> > 
> > 		
> >
>
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