PHP property overloading

<?php
/*

  Author by Kay Sackey
  Many thanks to http://latrine.dgx.cz/property-setters-and-getters-final-solution
  PHP Property overloading


class ATest extends Magic {
   // After the constructor fires this property is 'hidden', but you can access it directly through $_myAttribute
   protected $myAttribute = property;


   public function __construct(){
      parent::__construct();  // Remember to call the Magic constructor first if your class defines a constructor
   }

//      I use public functions for getters and setters because I only use this class to transition from class attributes towards getters/setters
//      You can use it anyway you like.

//     If you don't define a getter or a setter then he object attribute will behave just as you expect it.
//     e.g. $class->a = 5

   public function getMyAttribute(){
       // Do some complex logic to get the attribute
       return 0;
   }

   public function setMyAttribute(){
       // Do some complex logic to set the attribute
   }


*/

//
// This has only been updated to not throw a notice under E_STRICT, and to make it easier to integrate into existing classes

// define new "like-keyword"
// value is short and unusual string
define('property',   "\0\0");

class Magic{

    // magic
    protected $_props;

    /**
    * Universal setter.
    *
    * If property 'abc' is declared,
    * there must be setAbc() setter,
    * otherwise property is read-only
    */
    final private function __set($name, $value)
    {
        if (isset($this->_props[$name]))
          if (method_exists($this, 'set'.$name))
            $this->{'set'.$name}($value);
          else
            throw new Exception("Property '$name' is read-only.");
        elseif($name[0] === '_')
                $this->$name = $value;
        else
            throw new Exception("Undefined property '$name'.");
    }

    /**
    * Universal getter.
    *
    * If property 'abc' is declared,
    * there must be getAbc() getter,
    * otherwise variable $_abc
    */
    final private function __get($name)
    {

        if (isset($this->_props[$name]))
          if (method_exists($this, 'get'.$name))
            return $this->{'get'.$name}();
          else
            return $this->{'_'.$name};
        else
          throw new Exception("Undefined property '$name'.");
    }

    final private function __isset($name)
    {
        return isset($this->_props[$name]);
    }

    final private function __unset($name)
    {
        unset($this->_props[$name]);
    }

    final private function _property($obj)
    {
      // use cache (analyze object only once)
      static $cache;
      $item = & $cache[ get_class($obj) ];

      // look for properties
      // 1) get_object_vars prevents ObjectIteration
      // 2) outside of objects returns only public members (speed-up)

      if ($item === NULL) {
        $item = array();
        foreach (get_object_vars($obj) as $name => $value){
          if ($value === property) {
            $item[$name] = true;
            unset($obj->$name);
            $obj->{'_'.$name} = null;
          }
        }
        return $item;
      }


      foreach ($item as $name => $foo){
        unset($obj->$name);
        $obj->{'_'.$name} = null;
      }


      return $item;
    }

    function __construct()
    {
        // property initialization
        $this->_props = self::_property($this);
    }


}