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.

Making Movie Clip Components

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385

this.setColor(this.cp_ballColor);

this.setSize(this.cp_radius);

this.onEnterFrame = this.move;

// Remove component parameters from the instance (any property that starts

// with the prefix cp_ is a component parameters).

for (var p in this) {

if (p.indexOf("cp_") != -1) {

delete this[p];

}

}

};

Of course, now that we’ve changed our Ball constructor, we must modify our

initObject to use the component property names when creating ballSymbol instances

with attachMovie(). This lets us use one consistent constructor function, whether the

component is created manually at authoring time or programmatically at runtime.

Here’s the revised attachMovie() approach:

var initObj = new Object( );

initObj.cp_radius = 10;

initObj.cp_ballColor = 0xFF0000;

initObj.cp_x = 250;

initObj.cp_y = 250;

initObj.cp_velocity = {x:12, y:4};

// Create a ball.

this.attachMovie("ballSymbol", "redBall", 1, initObj);

If all clip instances of a subclass will be generated programmatically using

attachMovie() or duplicateMovieClip(), you should design the constructor to accept

parameters attached to a single

params object within the initObject. However, if you

are creating components that will be instantiated at authoring time, you should design

the constructor to accept individual component ...