Von: Derrell Lipman [mailto:[email protected]]
Gesendet: Mittwoch, 01. September 2010 15:22
An: qooxdoo Development
Betreff: Re: [qooxdoo-devel] Problem with addlistener
JavaScript does not have block-level scoping. All variable declarations
anyplace in a function are effectively moved to the top of the function. Your
icon variable used in the loop is the same variable in every instance of your
listener function, so it has the value it was last assigned. You don't,
anyplace, store the current value to create a closure that is unique to a
particular loop iteration.
Closures are an interesting beast, and are not available in most traditional
languages so seem strange. Once you get used to them they're really useful, but
until you do, they seem to act strangely. This was why I recommended, for the
time being, using the setUserData() method of widgets.
In this case, you can most easily solve the problem by creating a closure on
"this" (it appears to be a container, so let's call it "container") and passing
"icon" as the context to the listener function:
var iconarray = this.dbdatainstance.getIconArray();
var container = this; // Store the context which will be used in the
listener
for (var i=0; i < iconarray.getLength(); i++)
{
var icon = iconarray.getItem(i);
var button = icon.getButton();
button.addListener("dblclick", function(e) {
if(cws.Application.loginvalue == true){
container.moveObject(desktop, this); // note "this" is
the icon here
}
},icon); // pass icon as the context
}
Derrell
Thank you very much! Now it works!
Hari
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