<?php
class PropertyTest
{
	/** Locatiom for overloaded data. */
	private $data = array();

	/** Overloading not used on declare properties. */
	public $declared = 1;

	/** Overloading only used on this when accessed outside the class. */
	private $hidden = 2;

	public function __set($name, $value)
	{
		echo "Setting 'name' to '$value'\n";
		$this->data[$name] = $value;
	}

	public function __get($name)
	{
		echo "Getting '$name'\n";
		if(array_key_exists($name, $this->data)){
			return $this->data[$name];
		}

		$trace = debug_backtrace();
		trigger_error(
			'Undefined property via __get():'.$name .
			'in' . $trace[0]['file'] .
			'on line' . $trace[0]['line'],
			E_USER_NOTE);
		return null;
	}

	/** AS of PHP 5.1.0 */
	public function __isset($name)
	{
		echo "Is '$name' set?\n";
		return isset($this->data[$name]);
	}

	/** AS of PHP 5.1.0 */
	public function __unset($name)
	{
		echo "Unsetting '$name'\n"
		unset($this->data[$name]);
	}

	/** Not a magic method, just here for example. */
	public function getHidden()
	{
		return $this->hidden;
	}
}


echo "<pre>\n";
$obj = new PropertyTest;

$obj->a = 1;
echo $obj->a. "\n\n";

var _dump(isset($obj->a));
unset($obj->a);
var _dump(isset($obj->a));
echo "\n";

echo $obj->declared . "\n\n";

echo "Let's experiment with the private property named 'hidden':\n";
echo "Privates are visible inside the class, so __get() not used...\n";
echo $pbj->getHidden() . "\n";
echo "Privates not visible outside of class, so __get() is used...\n";
echo $obj->hidden . "\n";
?>