ActionScript for Flash MX: The Definitive Guide, Second Edition

This is the Title of the Book, eMatter Edition

Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Function Parameters Revisited

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The rules for creating timeline variables apply even if our function is a method of an

object. We won’t cover objects until Chapter 12, but for those familiar with object-

oriented programming, Example 9-2 shows code that proves the point. Observe that

x is defined on the timeline because it doesn’t exist in the local scope of newFunc( ).

Using unqualified variable references inside functions to affect timeline variables may

appear handy, but more often than not it is confusing, particularly in large projects.

It’s wise to take the ambiguity out of variable access by using qualified variable refer-

ences (i.e., prefix the variable with an explicit object reference, such as

this.x versus

x, as discussed in Chapter 2 under “Accessing Variables on Different Timelines”).

Function Parameters Revisited

Now that we’re comfortable with how functions work, let’s return to the topic of

function parameters. Our current discussion requires a little knowledge of objects, so

new programmers may want to read Chapter 12 before reading this section.

Number of Parameters

Earlier we saw that the parameters of a function are declared when the function is

created. Recall the syntax:

function funcName (param1, param2, ...paramn) {

statements

}

Perhaps surprisingly, the number ...