php builder pattern

class Meal 
{
	private $food;
	private $drink;
	
	public function setFood($f) {
		$this->food = $f;
	}
	public function setDrink($d) {
		$this->drink = $d;
	}
	
	public function getFood() {
		return $this->food;
	}
	public function getDrink() {
		return $this->drink;
	}
}

abstract class MealBuilder
{
	protected $meal;
	function __construct() {
		$this->meal = new Meal();
	}
	abstract protected function buildFood();
	abstract protected function buildDrink();
	
	public function getMeal() {
		return $this->meal;
	}
}

class SubMealBuilderA extends MealBuilder
{
	public function buildFood() {
		$this->meal->setFood('一个鸡腿堡');
		
	}
	public function buildDrink() {
		$this->meal->setDrink('一杯可乐');
	}
	public function getMeal() {
		return $this->meal;
	}
}

class SubMealBuilderB extends MealBuilder
{
	public function buildFood() {
		$this->meal->setFood('一个鸡肉卷');

	}
	public function buildDrink() {
		$this->meal->setDrink('一杯果汁');
	}
	public function getMeal() {
		return $this->meal;
	}
}

class KFCWaiter
{
	private $MealBuilder;
	
	public function setMealBuilder($mb) {
		eval("\$m= new {$mb}();");
		$this->MealBuilder = $m;
		return $this->MealBuilder;
	}
	public function construct() {
		$this->MealBuilder->buildFood();
		$this->MealBuilder->buildDrink();
		return $this->MealBuilder->getMeal();
	}
}

<?xml version="1.0" encoding="UTF-8"?>  
  <meal>  
	  <mealA>  
		  <name>SubMealBuilderA</name>   
	  </mealA> 
	  <mealB>  
		  <name>SubMealBuilderB</name>   
	  </mealB>  	  
  </meal> 

$mealstring = simplexml_load_file('meal.xml');
$waiter = new KFCWaiter();
foreach ($mealstring as $Submeal) {
	$waiter->setMealBuilder($Submeal->name);
	$meal = $waiter->construct();
	echo '套餐组成:';
	echo "<br>";
	echo $meal->getFood();
	echo "<br>";
	echo $meal->getDrink();
	echo "<br>";
	echo "<br>";
}