php hook system

hook.php

<?php
class hookSystem
{
    /**
     * @abstract Objects array
     * @access Private 
     */
    private static $objects = array();
    /**
     * @abstract Settings array
     * @access private
     */
    private static $settings = array();
    /**
     * @abstract The one and only instance allowed.
     * @access private
     */
    private static $instance;
    /**
     * @abstract Private constructor
     * @access private
     */
    private function __construct()
    {
        $this->storeCoreObjects();
    }
    /**
     * @abstract Store the core framework objects
     * @access private
     */
    private function storeCoreObjects()
    {
        //Store objects: $this->storeObject("database","db");
    }
    /**
     * @abstract Create the instance of the registry
     * @access public
     * @return self::instance
     */
    public static function singleton()
    {
        if (!isset(self::$instance)) {
            $obj = __class__;
            self::$instance = new $obj;
        }
        return self::$instance;
    }
    /**
     * @abstract Prevent cloning of the registry
     * @access public
     */
    public function __clone()
    {
        trigger_error('Cloning the registry is not permitted', E_USER_ERROR);
    }
    /**
     * @abstract Stores an object to the array
     * @access private
     * @param String $key
     * @param String $object
     * @return void
     */
    public function storeObject($object, $key)
    {
        require_once ('Objects/' . $object . '.class.php');
        self::$objects[$key] = new $object(self::$instance);
    }
    /**
     * @abstract Get an object from the array
     * @access public
     * @param String $key
     * @return object
     */
    public function getObject($key)
    {
        if (is_object(self::$objects[$key])) {
            return self::$objects[$key];
        }
    }
    /**
     * @abstract Store a setting to the registry
     * @access public
     * @param String $data
     * @param String $key
     * @return void
     */
    public function storeSetting($data, $key)
    {
        self::$settings[$key] = $data;
    }
    /**
     * @abstract Get a setting from the registry
     * @access public
     * @param String $key
     * @return Setting
     */
    public function getSetting($key)
    {
        return self::$settings[$key];
    }
}
?>