[DJMaze]

Class members can be overloaded to run custom code defined in your class by defining specially named methods (__set, __get, __call).
This is not adviced to use since it doesn't handle class inside class and it slows down your scripts.

However it can be used as nice factory system. The trick here is that you can make a factory of methods that you don't need often or need to be loaded before some script execution but not used unless certain actions are triggerd.

For an example you have a script that offers a HTML output template system but, one of your pages outputs RSS then it's useless to load the template class.
Instead you could use a factory with overloaders and that way the template is only loaded when it's realy needed to increase speed.

PHP Code:

<?php
class My_Handler
{
    protected $class_file;
    protected $class_name;
    protected $class_inst;

    public function __construct($class_name)
    {
        $this->class_name = $class_name;
        $this->class_inst = null;
    }

    public function __call($method, $args)
    {
        if (!$this->class_inst) $this->load_inst();
        $count = count($args);
        if ($count == 0) {
            return $this->class_inst->$method();
        } else if ($count == 1) {
            return $this->class_inst->$method($args[0]);
        } else if ($count == 2) {
            return $this->class_inst->$method($args[0], $args[1]);
        } else {
            $call[0] =& $this->class_inst;
            $call[1] = $method;
            return call_user_func_array($call, $args); # this is slow
        }
    }

    public function __get($nm)
    {
        if (!$this->class_inst) $this->load_inst();
        $this->class_inst->$nm;
    }
    public function __set($nm, $val)
    {
        if (!$this->class_inst) $this->load_inst();
        $this->class_inst->$nm = $val;
    }

    public function name() { return $this->class_name; }

    # Check if class is already loaded else load it into memory
    private function load_inst()
    {
        if ($this->class_inst) return;
        $file = strtolower($this->class_name).'.php';
        if (!class_exists($this->class_name, false) && !file_exists($file)) {
            throw new Exception("Class {$this->class_name} does not exist");
        }
        require_once($file);
        $this->class_inst = new $this->class_name($this);
    }

}

$template = My_Handler($template);

if ($_GET['rss']) {
    echo 'rss'; # template class NOT loaded
} else {
    $template->include('index.html'); # template class gets loaded
    $template->display();
}