PHP Decorator Class

<?
namespace Decorator;
/* the required files with previously defined classes */
use \Cart as CoreCart;
abstract class Decorator {
	/**
	 * Decorated object
	 * @var object Reference to wrapped object
	 */
	protected $obj;
	function __construct($obj = null) {
		if(is_object($obj)) {
			$this->obj = $obj;
		} else {
			$this->obj = new stdClass();
		}
	}
	/**
	 * On Missing Method
	 *
	 * When the decorator object does not have the called method implimentation attempt to call the wrapped/decorated object
	 *
	 * Pre/Post Method call processing. If you need to modify any of the data before or after any method calls, then you may
	 * declare a function for the class Decorator in this manner:
	 *
	 *   function PreHookMethodNameHere($arg1, $arg2, .... $argN)
	 *   		or
	 *   function PreHookMethodNameHere() {
	 *   	$args = func_get_ar
	 *   		...
	 *   	return;
	 *   }
	 *
	 * @param string $method
	 * @param array $args
	 */
	function __call($method, $args = array()) {
		/**
		 * PreHook MethodCalls
		 *
		 * preMethod function delcaration must either match called method or get_func_args().
		 * @var array
		 */
		if(method_exists($this, "PreHook".$method)) {
			//$args[] = 'func_get_args::test';
			call_user_func_array(array($this, "PreHook".$method), $args);
		}
		try {
			$results = call_user_func_array(array($this->obj, $method), $args);
		} catch(Exception $e) {
			throw new Exception("Call to missing method ".get_class($this->obj)."::$method()" );
		}
		/**
		 * PostHook Method Calls
		 *
		 * The results of the called ojbect method will be pushed on the original $args array.
		 * postMethod function declaration should use get_func_args() and pop called method results off
		 * then set any defaults of $args based on position if necessary
		 * @var array
		 */
		if(method_exists($this, "PostHook".$method)) {
			$args[] = $results;
			$results = call_user_func_array(array($this, "PostHook".$method), $args);
		}
		return $results;
	}
	//provide access to decorated class objects
	function __get($attr) {
		try {
			return $this->obj->$attr;
		} catch(Exception $e) {
			throw new Exception(get_class($this->obj)." has no member attribute '$attr'" );
		}
	}
}
/**
 * Implement BulkPricing
 *
 * Transparent Wrapper class to add bulkPricing for Cart and Order. Also provide a very easy method of disabling
 * this functionality, just comment out namespace declaration in pages that are declaring the cart like so:
 * 		use \Cart as CoreCart;
 * 		use \Decorator\Cart as Cart;
 * @author pgmiller
 */
abstract class BulkPricingCollectionDecorator extends Decorator {
	protected $collectionId;
	protected $collectionTable;
	protected $collectionColumn;
	protected $collectibleTable;
	protected $collectibleColumn;
	/**
	 * @var array
	 * $collection[$collectible->GetHash()] =>
	 * 		array(	'totalQty'=>(int),
	 * 				'list'=>array('collectibleId'=>$collectible)
	 * 		)
	 */
	protected $collection = array();
	protected $bulkPricingTiers = array();
	function __construct($obj, $configs = array()) {
		parent::__construct($obj);
		$default = array(
			'collectionId'=>0,
		);
		$configs = array_merge($default, $configs);
		$this->SetCollectionId($configs['collectionId']);
	}
	function SetCollectionId($id) {
		$id = filterInt($id);
		if($id)
		{
			$this->collectionId = $id;
			return true;
		}
		else
			return false;
	}
	/**
	 * Build a the bulkPricing detials
	 *
	 * @param $collectionId Primary Key for entire group of objects, in this case the cartId or orderId
	 * @param $eventId
	 * @return returns collection by reference in case it is needed.
	 */
	function GetBulkPricingCollectionArray($collectionId = 0, $timeZoneCode = 'America/Denver')
	{
		if($collectionId = filterInt($collectionId))
			$this->SetCollectionId($collectionId);
		$timeZoneCode = (trim($timeZoneCode) == '') ? 'America/Denver' : trim($timeZoneCode);
		/*
		.... other code here not show
		*/
		return $this->collection;
	}
	function CalcBulkImagePrice($quantity, $bulkPricingTiers, $basePrice = 0)
	{
		$bulkPrice = false;
		if($bulkPricingTiers && is_array($bulkPricingTiers))
		{
			if(filterInt($quantity) >= $bulkPricingTiers[0]->quantity)
			{
				foreach($bulkPricingTiers as $tier)
				{
					if($quantity >= $tier->quantity)
						$bulkPrice = $tier->price;
					else
						break;
				}
			}
		}
		return (!$bulkPrice && $basePrice) ? $basePrice : $bulkPrice;
	}
}
/**
 * Concrete BulkPricing Wrapper
 *
 * Concrete Wrapper class to add bulkPricing for the cart.
 *
 * @author pgmiller
 */
class Cart extends BulkPricingCollectionDecorator {
	function __construct($db, $configs=array()) {
		parent::__construct(new CoreCart($db), $configs);
		$this->collectionTable 		= 'cart';
		$this->collectionColumn 	= 'cartId';
		$this->collectibleTable 	= 'cartItem';
		$this->collectibleColumn 	= 'cartItemId';
	}
	/**
	 * Build and return details of shopping cart
	 *
	 * Because the \CoreCart class calls GetPhotoCartItemList on itself $this-> ... the call bypasses the decorator
	 * class and so a simple solution is to catch the original call and pass the bulkPricing modified photoItems
	 * along with the call.
	 *
	 * @param $cartId
	 * @param $sessionId
	 * @param $eventId
	 * @param $timeZoneCode
	 */
	function GetCart($cartId, $sessionId, $eventId = "0", $timeZoneCode = 'America/Denver')
	{
		//echo "<pre>".print_r(func_get_args(),true)."</pre>";
		$itemList = $this->GetCartItemList($cartId, $eventId, $timeZoneCode);
		return $this->obj->GetCart($cartId, $sessionId, $eventId, $timeZoneCode, $itemList);
	}
	function PreHookGetCartItemList($cartId, $eventId = "1", $timeZoneCode = 'America/Denver') {
		//echo "<pre>".__METHOD__." ".print_r(array($cartId, $eventId, $timeZoneCode),true)."</pre>";
		//echo "<pre>".__METHOD__." ".print_r(func_get_args(),true)."</pre>";
		$this->GetBulkPricingCollectionArray($cartId, $eventId, $timeZoneCode);
	}
	function PostHookGetCartItemList($cartId, $eventId = "1", $timeZoneCode = 'America/Denver') {
		$args = func_get_args();
		$cartItems = array_pop($args); //results of GetCartItemList on top of stack
		$args[] = $cartItems;
		if(is_array($cartItems))
		{
			foreach ($cartItems as $index=>$cartItem)
			{
				/* all cartItem post processing */
			}
		}
		return $cartItems;
	}
}