PluggableFactory

Last edit May 10, 2010
An extension to the AbstractFactoryPattern is the PluggableFactory proposed by JohnVlissides. See:

-- ArieVanDeursen

Briefly, there is a single factory class, instances of which contain prototype instances of the things to be created; these instances are then cloned to satisfy creation requests. Thus, the PluggableFactory pattern hides the PrototypePattern, using the factory as a facade (FacadePattern).

For example (in JavaLanguage): 

 abstract class Button
 {
 	abstract public Object clone();
 }


 class WindowsButton extends Button
 {
 	// implementation of a Windows button
 }


 class MotifButton extends Button
 {
 	// implementation of a Motif button
 }


 class ButtonFactory
 {
 	private Button btn ;
 	public Button create()
 	{
 		return (Button)btn.clone() ;
 	}
 }
The normal AbstractFactory approach would make ButtonFactory abstract, and then add WindowsButtonFactory and MotifButtonFactory subclasses; it also wouldn't need Button to be Cloneable.

The advantage of a PluggableFactory is that it eliminates the proliferation of factory subclasses. The disadvantage is that the products must be cloneable, or otherwise duplicatable in some way.

A nominally related, but distinct, pattern for using AbstractFactory as the export component in PluginArchitecture is described in the page on AbstractFactory.

CategoryPattern, CategoryPatternFactory