root/trunk/src/main/php/net/stubbles/events/stubLazyEventListener.php

<?php
/**
 * Class for lazy loading of concrete event listeners.
 * 
 * @author      Frank Kleine <mikey@stubbles.net>
 * @package     stubbles
 * @subpackage  events
 */
stubClassLoader::load('net::stubbles::events::stubEvent',
                      'net::stubbles::events::stubEventListener'
);
/**
 * Class for lazy loading of concrete event listeners.
 *
 * @package     stubbles
 * @subpackage  events
 */
class stubLazyEventListener extends stubSerializableObject implements stubEventListener
{
    /**
     * the full qualified name of the class to execute in case the event happens
     *
     * @var  string
     */
    protected $fqClassName;

    /**
     * constructor
     *
     * @param  string  $fqClassName  full qualified name of the class to execute
     */
    public function __construct($fqClassName)
    {
        $this->fqClassName = $fqClassName;
    }

    /**
     * returns the class name of the lazy loaded class
     *
     * @return  string
     */
    public function getLazyClassName()
    {
        return $this->fqClassName;
    }

    /**
     * handles an event
     *
     * @param   stubEvent  $event  event that triggered this event listener
     * @throws  stubException
     */
    public function handleEvent(stubEvent $event)
    {
        $this->createInstance()->handleEvent($event);
    }

    /**
     * returns true if listener should be removed after first notification or not
     *
     * @return  bool
     * @throws  stubException
     */
    public function autoremove()
    {
        return $this->createInstance()->autoremove();
    }

    /**
     * helper method to create the concrete event listener instance
     *
     * @return  stubEventListener
     * @throws  stubRuntimeException
     */
    protected function createInstance()
    {
        static $instance;
        if (null === $instance) {
            $className = stubClassLoader::getNonQualifiedClassName($this->fqClassName);
            if (class_exists($className, false) == false) {
                stubClassLoader::load($this->fqClassName);
            }
            
            $instance = new $className();
        }
        
        if (($instance instanceof stubEventListener) == false) {
            throw new stubRuntimeException('Lazy loaded event listener ' . $this->fqClassName . ' is not an instance of ' . $this->getPackageName() . '.stubEventListener.');
        }
        
        return $instance;
    }
}
?>