Weblabor

class ShopProduct {
   public $title;
   public $producerMainName;
   public $producerFirstName;
   public $price;

   function __construct( $title, $firstName, $mainName, $price ) {
       $this->title = $title;
       $this->producerFirstName = $firstName;
       $this->producerMainName = $mainName;
       $this->price = $price;
   }

   function getProducer() {
       return "{$this->producerFirstName}". " {$this->producerMainName}";
   }

   function getSummaryLine() {
       $base = "{$this->title} ( {$this->producerMainName}, ";
       $base .= "{$this->producerFirstName} )"; 
       return $base;
   }
}

class CdProduct extends ShopProduct {
	public $playLength;
	
	function __construct($title, $firstName, $mainName, $price, $playLength) {
		parent::__construct($title, $firstName, $mainName, $price);
		$this->playLength = $playLength;
	}
	
	function getPlayLength() {
		return $this->playLength;
	}

}

parent::__construct($title, $firstName, $mainName, $price);