This isn't the problem case. Think about:
Collection c = new ArrayList();
ObservableCollection oc = CollectionUtils.observableCollection(c);
SynchronizedCollection sc = CollectionUtils.synchronizedCollection(oc);
oc.addListener(new CollectionListener() {
public void changed(CollectionEvent e) { Collection eventCollection =
e.getCollection() }
});
c.add("");
Fails - but all decorators ban this because c is decorated
oc.add("");
Sends event OK - eventCollection == oc, but all decorators ban this because
oc is decorated
sc.add("");
Sends event OK - BUT eventCollection == oc.
This is a problem, as if the listener then uses the collection, it will not
be synchronized. Big problem.
Stephen
----- Original Message -----
From: "Michael Heuer" <[EMAIL PROTECTED]>
To: "Jakarta Commons Developers List" <[EMAIL PROTECTED]>
Cc: <[EMAIL PROTECTED]>
Sent: Thursday, August 14, 2003 11:02 PM
Subject: Re: [collections] NotifyingCollections - capturing rich non-uniform
data
>
> On Thu, 14 Aug 2003, Stephen Colebourne wrote:
>
> > <snip>
> >
> > The biggest problem with all this is that the collection returned by
> > getSource() on the event. If the observed collection is wrapped (eg. by
a
> > SyncronizedCollection) then getSource() SHOULD return the wrapped
> > collection, but it can't as it doesn't know about it. This problem
applies
> > to all designs so far.
>
> Is this also a problem? It's general to all of the delegation
> implementations.
>
>
> private boolean heardChange = false;
>
> public void testChangeToBackingCollection()
> {
> Collection c = new ArrayList();
> ObservableCollection oc = CollectionUtils.observableCollection(c);
> oc.addListener(new CollectionListener()
> {
> public void changed(CollectionEvent e) { heardChange = true; }
> });
>
> c.add("hello");
>
> assertTrue("heardChange == true", heardChange == true);
> }
>
>
> I don't think it's possible to make this test pass -- just a
> shortcoming of the wrapper design. That's why I was looking into
> aspect-based implementations.
>
> michael
>
>
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