ActionScript for Flash MX: The Definitive Guide, Second Edition

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Chapter 10: Events and Event Handling

Code Reusability

When using event handlers and listeners, don’t forget the code-centralization princi-

ples discussed in Chapter 9. Avoid unnecessary duplication and intermingling of

code across movie elements. If you find yourself entering the same code in more than

one event handler’s body, you should try defining it in a single function and point-

ing each event handler to that function. Try generalizing your code, pulling it off the

object and placing it in a code repository somewhere in your movie; global code used

throughout a movie should be attached to the

_global object.

In almost all cases, it’s a poor idea to hide statements inside an on( ) or onClipEvent( )

handler. Remember that encapsulating your code in a function makes your code

reusable and easy to find. This is particularly true of buttons—I rarely place any code

on a button in Flash MX, and I rarely use more than a single function-invocation

statement in a Flash 5 on( ) handler. For movie clips, you’ll need to employ keener

judgment, as placing code directly on clips can often be a healthy part of a clean, self-

contained code architecture. Experiment with different approaches until you find the

right balance for your needs and skill level. Regardless, it always pays to be