pseudostereo

I'm trying to modify a variable using the Task object, but even though the value of the variable gets passed to the task when it is first created, it doesn't get updated each time the task runs.

Here's an example, where I'm trying to smoothly fade the alpha channels of three objects. What am I doing wrong?

    var myTask = new Task(fadeTask,this,alpha[a]); 

        arguments.callee.task.cancel();

alpha[a] does get set to 0.99 the first time the function is called, but then it just stays there.

function fadeThis(a) {
	alpha[a] = 1.0
	var myTask = new Task(fadeTask,this,alpha[a]); 
	myTask.interval = 10;
	myTask.repeat();
}

function fadeTask(anAlpha) {
	anAlpha -= 0.01
	if (anAlpha
		anAlpha=0;
		arguments.callee.task.cancel();
	}
}

modifying-a-variable-with-the-task-object

The following doesn't work since the anAlpha is passed by value, not 

by reference, as it is a value. You'll need to figure out a different 

way to either passs as reference(objects are by reference, but 

numbers are by value). there are a few ways to accomplish this. The 

quickest/dirtiest way would be to use globals. You could also 

accomplish by creative use of an object instance, or function 

properties (you might want to do some web searches on functions and 

lexical closures for some examples of this last approach).

In your example, however, it looks like alpha is a global anyway so 

you could just pass in the alpha array index.

The following doesn't work since the anAlpha is passed by value, not  
by reference, as it is a value. You'll need to figure out a different  
way to either passs as reference(objects are by reference, but  
numbers are by value). there are a few ways to accomplish this. The  
quickest/dirtiest way would be to use globals. You could also  
accomplish by creative use of an object instance, or function  
properties (you might want to do some web searches on functions and  
lexical closures for some examples of this last approach).

In your example, however, it looks like alpha is a global anyway so  
you could just pass in the alpha array index.

Got it, thanks Joshua. The value/reference distinction always trips me up.

modifying a variable with the Task object