Re: [java-gnome-hackers] WeakReferences going away

[Philip A. C. <pch...@pc...>]

On Thu, 2003-02-27 at 12:10, Tom Ball wrote:
> In this case, I think the problem is related to my style of app
> development:  I never keep listener references in my app, but instead
> just attach them to a widget and forget about them:
>=20
> 	Button cancelButton =3D fontsel.getCancelButton();
> 	cancelButton.addListener(new ButtonListener() {
> 		public void buttonEvent(ButtonEvent event) {
> 		    if (event.isOfType(ButtonEvent.Type.CLICK)) {
> 			fontsel.destroy();
> 		    }
> 		}
> 	    });
>=20

Yes, this does seem to be an issue of coding style.  Many, many code
examples of Swing use inner classes as event handlers.  Not to start any
flame wars, but I *personally* dislike inner classes and very rarely (if
ever) use them.  However, my personal preference does not matter.  Java
allows developers to do this and many swing developers (and some IDEs w/
GUI designers) use this heavily.  Therefore, we should code to support
*both* methods.  (Disclaimer:  I realize that the use of inner classes
are not the only possible cause of this problem, but would probably be
the most likely.)

> But there I think good documentation is the best one can do here.

Then good documentation it shall be.  Even if this weren't a problem,
good documenatation is a must.  :-)

> If memory isn't too big an issue (or if we want to create a "debug"
> version of our libraries), we can keep a WeakReference'd static list in
> each listener class of the current listeners and what widget they are
> listening to.  Some key sequence (such as Ctl-Shift-F10) can trigger the
> dumping of this list out to the command line for debugging purposes.=20
> This beats poking around in a heap profiler, and is much more likely to
> be used by app developers.  If you want, I can add this feature soon.

I think that this would be a *very* nice feature in a "debug" version.

--=20
Philip A. Chapman

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