MACROMEDIA FLASH 8-LEARNING ACTIONSCRIPT 2.0 IN FLASH Manual page 760

About using functions
Reuse blocks of code whenever possible. One way you can reuse code is by calling a function
multiple times, instead of creating different code each time. Functions can be generic pieces of
code; therefore, you can use the same blocks of code for slightly different purposes in a SWF
file. Reusing code lets you create efficient applications and minimize the ActionScript 2.0
code that you must write, which reduces development time. You can create functions on a
timeline, in a class file, or write ActionScript that resides in a code-based component, and
reuse them in a variety of ways.
If you are using ActionScript 2.0, avoid writing functions on a timeline. When you use
ActionScript 2.0, place functions into class files whenever possible, as the following
example shows:
class Circle {
public function area(radius:Number):Number {
return (Math.PI*Math.pow(radius, 2));
}
public function perimeter(radius:Number):Number {
return (2 * Math.PI * radius);
}
public function diameter(radius:Number):Number {
return (radius * 2);
}
}
Use the following syntax when you create functions:
function myCircle(radius:Number):Number {
//...
}
Avoid using the following syntax, which is difficult to read:
myCircle = function(radius:Number):Number {
//...
}
760 Best Practices and Coding Conventions for ActionScript 2.0