Adam Steffen wrote:
I'm not experienced with javascript at all so bear with me. I'm trying
to make a Web Interface with many buttons, check boxes, selection
lists, etc. and associate with these widgets a set of data. So that
changing the selections on the interface update the data set.
Using qooxdoo, I made a class to hold the data, and added member
functions that will update the data set, based on passed variables. I
then created an interface window with all the widgets. What I want to
do is associate the member functions of the data set with listeners of
the corresponding widgets. My simple brain would like to do the
following:
In window interface class:
/ ...
mycheckboxgroup.addListener("changeSelection",
myDataSet.updateFunction(data_name,mycheckboxgroup), myDataSet);
.../
Then in data set class:
/ ...
updateFunction : function(data_name,checkbox)
{
value = checkbox.getSelected().getValue();
this.setData(data_name,value);
}
.../
This implimentation just executes the updateFunction once as the
listener is added. Based on what I've read, this is because the
function argument should be a pointer to a function rather than a
function() call.
Right, the second argument has to evaluate to a function object, to be
precise.
But then how do you pass arguments to the Listener as it is constructed?
You don't. The listener function is monadic, taking an event object
instance as a single argument. This is the listener protocol you have to
adhere to. You say something like
...addListener("event", function (e) { var d = e.getData(); ....}, obj);
e will be provided at run time and is all you get for the listener
invocation. The type of e can vary according to the class and event
you're registering with, so check the API for that.
Is there a way to create a generic listener function that takes
variable arguments? I don't want to have to write the code for each
new listener function for each of the 50 checkboxgroups i have, but I
want to add a listner to each and associate that listener to a data
set based on a variable.
You can write a listener factory like
function makeListener (specialArg) {
return function (e) { /* use event e and specialArg here */ };
}
and then call it when you add a listener
...addListener("event", makeListener(specialArg), obj);
HTH,
T.
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