Hi Marius,
yes, you are right, the listener should be removed. A smart solution
would be to remove the listener when the class will be disposed, but you
can't remove a listener with an anonymous callback method. So the first
step is to remove the anonymous calback method and also take care that
the listener is only once added. And at the end remove the listener in
the destruct method.
Here a example that shows it:
qx.Class.define("my.cool.Class",
{
// Do stuff...
members : {
this.__onUpdateListenerID : null,
// Do stuff...
__applyDataModel: function(dataModel) {
// Do some stuff...
if (this.__onUpdateListenerID == null) {
this.__onUpdateListenerID = snProxy.addListener("update",
this.__onUpdate, this);
}
},
this.__onUpdate : function() {
this.debug(this);
this.debug(this.__rootNode);
this.debug(this.__rootNode.getChildren());
this.refreshTree();
}
},
destruct : function() {
if(this.__onUpdateListenerID != null) {
// Do stuff to get snProxy
snProxy.removeListener("update", this.__onUpdate, this);
}
});
Cheers,
Chris
Am 23.09.2010 12:15, schrieb Marius Austerschulte:
I think I know the reason now: When the apply-Method is called on my
Tree object the first time, I don't get that error, the Tree isn't
disposed. When that method is called the second time it's called on a
new Tree instance that had been created shortly before. Again, a new
snProxy object is created and the "update"-event listener is added to
it. However, the old Tree instance still exists together with its
snProxy object that still fires the "update"-event although the Tree
it is contained in is already disposed (since it is not referenced
anymore).
Since there are multiple snProxys now the event handler function is
called multiple times but only in the last call the event handler
function refers to the current non-disposed Tree (I didn't recognize
that at first sight because the application broke on an error and
stopped running and only let the first "update"-event listener process
its code). The snProxy object itself isn't disposed because it is
referenced in an event listener of an object that still exists.
So if I add
if (!this.isDisposed()) {
this.debug(this);
// do something
}
to the event handler the program runs. But I think this solution is
not elegant. The event handler is still called by objects that
shouldn't exist anymore. I think I'll try to add a method that removes
all the event listeners that could cause such problems.
2010/9/22 Christian Hagendorn <[email protected]
<mailto:[email protected]>>
Am 22.09.2010 16:04, schrieb Marius Austerschulte:
> Great! That seems to be the reason! this.isDisposed() and
> this.__rootNode.isDisposed() are both true.
> But then why is it disposed? I still have a reference that points to
> that object.
Hi Marius,
I don't know what exactly is the reason in your case, maybe your
application does it. You can try to debug it buy adding a this.trace()
in the destruct function [1] in the class which has the appear method.
The stack trace should show how dispose/destroy the qooxdoo object.
Keep in mind that dispose and destroy has a differer meaning here. It
just means that a qooxdoo object is cleaned up for garbage
collection. A
qooxdoo dispose/destroy removes for example all DOM references so that
the garbage collector can remove the object from memory if no
reference
exist in your application.
Cheers,
Chris
[1]
http://manual.qooxdoo.org/1.2.x/pages/core/oo_feature_summary.html#destructor
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