How to call a function

Question

As part of my attempts to make FLEX 508 compliant, I've tried several things.  But this question is about basic FLEX in general.  What I'm trying to do is to call a routine (that will someday work and make FLEX compliant I hope).  Here is the basic layout in the mxml file:
  <mx:Script source="/scripts/FSUtil.as" />
  <mx:Script source="/scripts/FSCalc.as" />
  <mx:Script source="/scripts/FSLangSwitch.as" />
  <mx:Script>
      <![CDATA[
          accessibleSet();
      ]]>
  </mx:Script>
"accessibleSet" is located in the FSUtil.as file.  The error from the invocation above is:
1180: Call to a possibly undefined method accessibleSet.
This is what it looks like (note the code creates an error):
public function accessibleSet():void {
    headerDHSImage.accessibilityProperties.description = 'State of Illinois Department of Human Services logo';
The error is:
1120: Access of undefined property headerDHSImage.
But I don't think the basic idea of calling a function from the script section of an mxml file is affected by this.
Just for completeness, headerDHSImage is defined in a component called DHSHeader.mxml as:
    <mx:Image id="headerDHSImage"
        source="images/DHSLogo.gif"
        toolTip="State of Illinois Department of Human Services Logo"
        left="5" top="5"/>
This component is displayed when the application runs so I know that connection is working.
Recap:
I want to call a function from the script area of an mxml file, but am not sure of the protocol.
Thanks,
Jerry

Answer 1

> If I understand it at all, then in the mxml application tag you can only refer to functions
> that are within a naked script tag (only locally).  That is, you can't refer to a function
> that is in an associated script file via the script source method.
No, this is incorrect. There is no difference between declaring a function like accessibleSet() within the <Script> tag and declaring it in an AS file included by a <Script> tag. The problem is where you can call that function from. You normally do not write "loose code" in a <Script> tag like
<Script>
    accessibleSet();
</Script>
If you do, it actually becomes part of an autogenerated class initialization ("cinit") method emitted by the compiler, which isn't what you're expecting, because at class initialization time no instances even exist and you can only read and write static vars.
Another way to understand it is this: When you write an MXML file, you are writing a class. For example, suppose you write MyApp.mxml as
<mx:Application>
    <mx:Script>
        accessibleSet();
    <mx:Script>
    <mx:Button id="b"/>
</mx:Application>
This is more-or-less equivalent to writing the AS class
public class MyApp extends Application
    accessibleSet();
    var b:Button = new Button();
If you are familiar with writing classes, you should see the problem here: A class body doesn't normally contain loose function calls or other loose statements. Instead, a class body is supposed to contain 'const', 'var', and 'function' declarations. So you need to call a method like accessibleSet() inside another method -- such as an event handler -- that runs at a well-defined time.
BTW, you are probably going to confuse yourself further if you continue splitting your code for a single application into multiple AS files which you then include with <Script> tags. All of this code goes into one class and therefore it really belongs either inside the <Script> tag itself or in a single AS file brought in by a single <Script> tag. You need to think in terms of classes, not files.
Gordon Smith
Adobe Flex SDK Team