RE: [aspectj-users] AspectJ and memory management

["Gregor Kiczales" <gregor@xxxxxxxxx>]

> Rickard says:
>
> Anyway, Wes and I resolved the terminology issues off-list and it 
> appears what I want to do can't be done in AspectJ.
> 

I thought the following code, that we exchanged mail about last night,
does do what you want. In what way doesn't it work?

/*
 * Here's an aspect that associates a lot of extra state with
 * some target type. But we want to be sure not to allocate 
 * all that storage unless we really need it. So we use a
 * lazy allocation strategy for it.
 */
abstract aspect PersistenceOrSomething {

  protected interface HPoS {}; //marker type
                               //stands for HasPersistenceOrSomething

  private static StateBlock {
    private Mumble mumble;
    private Frotz  frotz;
    ...<many more fields>...
    StateBlock() { /*appropriate initialization*/ }
  }

  private StateBlock Target.state = null;

  /* these are the accessor methods for the state */
  public Mumble HPoS.getMumble() { return state.mumble; }
  public Frotz  HPoS.getFrotz () { return state.frotz;  }
  ...<many more accessors>...

  /* make sure the state is actually allocated before any accessor runs */

  before(HPoS hpos): within(HasPersitenceOrSomething) 
                    && execution(* HPoS.get*())
                    && this(hpos) {
      if(hpos.state == null)
          hpos.state = new StateBlock();
  }

  <and then the rest of your aspect is here>

}

aspect Foo extends HasPersistenceOrSomething {

  declare parents: SomeSpecificClass implements HPoS;

}