ClassFactory  - AS3 Flex

Package	mx.core
Class	public class ClassFactory
Inheritance	ClassFactory Object
Implements	IFactory
Subclasses	ButtonBarButtonClassFactory, ContextualClassFactory

Language Version:

ActionScript 3.0

Product Version:

Flex 3

Runtime Versions:

Flash Player 9, AIR 1.1

A ClassFactory instance is a "factory object" which Flex uses to generate instances of another class, each with identical properties.

You specify a generator class when you construct the factory object. Then you set the properties property on the factory object. Flex uses the factory object to generate instances by calling the factory object's newInstance() method.

The newInstance() method creates a new instance of the generator class, and sets the properties specified by properties in the new instance. If you need to further customize the generated instances, you can override the newInstance() method.

The ClassFactory class implements the IFactory interface. Therefore it lets you create objects that can be assigned to properties of type IFactory, such as the itemRenderer property of a List control or the itemEditor property of a DataGrid control.

For example, suppose you write an item renderer class named ProductRenderer containing a showProductImage property which can be true or false. If you want to make a List control use this renderer, and have each renderer instance display a product image, you would write the following code:

  var productRenderer:ClassFactory = new ClassFactory(ProductRenderer);
  productRenderer.properties = { showProductImage: true };
  myList.itemRenderer = productRenderer;

The List control calls the newInstance() method on the itemRenderer to create individual instances of ProductRenderer, each with showProductImage property set to true. If you want a different List control to omit the product images, you use the ProductRenderer class to create another ClassFactory with the properties property set to { showProductImage: false }.

Using the properties property to configure the instances can be powerful, since it allows a single generator class to be used in different ways. However, it is very common to create non-configurable generator classes which require no properties to be set. For this reason, MXML lets you use the following syntax:

  <mx:List id="myList" itemRenderer="ProductRenderer">

The MXML compiler automatically creates the ClassFactory instance for you.

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