Source for file Exception.php

<?php
/**
 * PHLY - PHp LibrarY
 *
 * PHLY is a library of PHP classes designed with the following intentions:
 * - Loosely coupled; dependencies should be few, and no base class should be
 *   necessary.
 * - Extendible; all classes should be easily extendible. This may be via
 *   observers, interfaces, adapters, etc.. The base class should solve 80% of
 *   usage, and allow extensions to the class to fill in the remainder.
 * - Designed for PHP5 and up; all classes should make use of PHP5's features.
 * - Documented; all classes should minimally have excellent API-level
 *   documentation, with use cases in the class docblock.
 * - Tested; all classes should have (passing) unit tests accompanying them.
 * - Open source and commercial friendly; all classes should use a
 *   commercial-friendly open source license. The BSD license is one such
 *   example.
 *
 * @license New BSD, http://www.opensource.org/licenses/bsd-license.php
 * @package Phly
 * @copyright 2006 - Present, Matthew Weier O'Phinney
 */
 
/**
 * Phly Exception Handling
 *
 * Phly_Exception implements an Observer pattern. You may build observer
 * classes that receive notifications when Phly_Exceptions (or classes
 * derived from it) are raised. Such classes need only have an event() method
 * that accepts a Phly_Exception object, and have to register their class or
 * an instance with Phly_Exception using {@link attach()}.
 *
 * @category Phly
 * @subpackage Phly_Exception
 * @copyright 2006 - Present, Matthew Weier O'Phinney
 * @author Matthew Weier O'Phinney <mweierophinney@gmail.com>
 * @version @release-version@
 */
class Phly_Exception extends Exception 
{
    /**
     * Array of observers
     * @var array 
     * @static
     * @access protected
     */
    private static $observers = array();
 
    /**
     * Constructor
     *
     * @access public
     * @param string 
     * @param int 
     * @param int 
     */
    public function __construct($message, $code = 0) 
    {
        parent::__construct($message, $code);
 
        $this->notify();
    }
 
    /**
     * String representation of exception
     * 
     * @access public
     * @return void 
     */
    public function __toString()
    {
        return __CLASS__ . ': [' . $this->code . ']: ' . $this->message . "\n";
    }
 
    /**
     * Attach an observer
     * 
     * @static
     * @access public
     * @param string|object $class Classname or object
     * @return void 
     */
    final public static function attach($class)
    {
        if (is_object($class) || class_exists($class)) {
            array_push(self::$observers, $class);
        }
    }
 
    /**
     * Notify observers of an error event
     * 
     * @access public
     * @return void 
     */
    final public function notify()
    {
        foreach (self::$observers as $class) {
            if (is_callable(array($class, 'event'))) {
                call_user_func(array($class, 'event'), $this);
            }
        }
    }
}