EventList Design

[Compulinkltd]

I know it's way too late in the ballgame to even think about redesigning
something as foundational as EventList, but I can't help but wonder if
ListModel isn't Sun's intended interface to observe fine-grained changes
to a list.  If that is the case, perhaps EventList could have been
defined as:

public interface EventList<E> extends List<E>, ListModel {
    public ReadWriteLock getReadWriteLock();
    public ListEventPublisher getPublisher();
};

I can see some advantages to using interfaces that Sun has already
predefined to interface more easily with Swing.  One advantage I note is
that the ListDataListener interface works in terms of intervals so
operations could be batched.  For example, an operation like addAll
would result in a single call to intervalAdded instead of a separate
event for every object added.

What got me thinking about this is that JGoodies binding defines an
ObservableList that is both a List and a ListModel.  What seems to be
lacking are the clever pipeline and locking concepts that GL has.  
Perhaps there is a way to combine the ideas?

Bruce

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[James Lemieux]

Bruce,

   ListModel falls down in one key area (as do all other implementations of Observable collections). It doesn't describe *arbitrary* change to the List. It assumes all of the change types for a single event are uniform.

i.e. in a single ListEvent, all you do is add elements, or remove elements, or update elements.

This limits what you are able to do with it in a lot of interesting cases.

e.g.
- amalgamate multiple ListEvents into a single uber-ListEvent (ThreadProxyEventList)
- allow something external to demark the true start and stop to List change (the new NestableEventsList)
- reliable network code with GL that need not consider partial failure

It's a lot harder to describe *arbitrary changes* to a List, but in end, we think the benefits are worth it.

James

On 10/24/07, Bruce Alspaugh <compulinkltd@...> wrote:

I know it's way too late in the ballgame to even think about redesigning
something as foundational as EventList, but I can't help but wonder if
ListModel isn't Sun's intended interface to observe fine-grained changes
to a list.  If that is the case, perhaps EventList could have been
defined as:

public interface EventList<E> extends List<E>, ListModel {
    public ReadWriteLock getReadWriteLock();
    public ListEventPublisher getPublisher();
};

I can see some advantages to using interfaces that Sun has already
predefined to interface more easily with Swing.  One advantage I note is
that the ListDataListener interface works in terms of intervals so
operations could be batched.  For example, an operation like addAll
would result in a single call to intervalAdded instead of a separate
event for every object added.

What got me thinking about this is that JGoodies binding defines an
ObservableList that is both a List and a ListModel.  What seems to be
lacking are the clever pipeline and locking concepts that GL has.
Perhaps there is a way to combine the ideas?

Bruce

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