[webbeans-dev] removeObserver type

[Clint Popetz]

Now that I'm thinking about it, I wrote "the observer should be removed for
all events for which it is registered" but because addObserver() is typed to
Observer<T>, and because you can't implement the same interface twice (even
with different parameterizations) any given instance can only be registered
once.   Well, it could be registered more than once, but the implementation
(and possibly the spec) could prohibit that, because it's meaningless.

In that case, I have no problem with the semantics of removeObserver.  But
the <?> means I'd have to rewrite a lot of observer storage/lookup code, and
it's not symmetric with addObserver(), so I wonder what the advantage of the
wildcard is.

-Clint


On Wed, May 27, 2009 at 2:35 PM, Gavin King <gavin.king at gmail.com> wrote:

> yes, that's what it means, though I must admit that when I made that
> change it was not totally clear to me that it was the right thing to
> do :-/
>
> Probably needs a bit more discussion...
>
> On Wed, May 27, 2009 at 11:59 AM, Clint Popetz <cpopetz at gmail.com> wrote:
> > Hi,
> >
> > The spec defines BeanManager.removeObserver to have a wildcard type:
> >
> > public void removeObserver(Observer<?> observer);
> >
> > and says "The container must stop sending event notifications to the
> > deregistered observer."  Does that sentence, taken with the wildcard
> type,
> > imply that the observer should be removed for all events for which it is
> > registered?  Currently ManagerImpl implements storage of observers as a
> map
> > from EventType -> Observer, which means removal of an observer without
> > knowing its event type would be linear in # observers, unless I change
> the
> > implementation.
> >
> > Thanks,
> > -Clint
> >
> >
> > --
> > Clint Popetz
> > http://42lines.net
> > Scalable Web Application Development
> >
> > _______________________________________________
> > webbeans-dev mailing list
> > webbeans-dev at lists.jboss.org
> > https://lists.jboss.org/mailman/listinfo/webbeans-dev
> >
> >
>
>
>
> --
> Gavin King
> gavin.king at gmail.com
> http://in.relation.to/Bloggers/Gavin
> http://hibernate.org
> http://seamframework.org
>



-- 
Clint Popetz
http://42lines.net
Scalable Web Application Development
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