类成员的访问方式和权限

以下为引用的内容：
＜?php
   class Widget
   {
       private $name;
       private $price;
       private $id;

       public function __construct($name, $price)
       {
           $this->name = $name;
           $this->price = floatval($price);
           $this->id = uniqid();
       }

       //checks if two widgets are the same
       public function equals($widget)
       {
           return(($this->name == $widget->name)AND
               ($this->price == $widget->price));
       }

       protected function getName()
       {
           return($this->name);
       }
   }

   class Thing extends Widget
   {
       private $color;

       public function setColor($color)
       {
           $this->color = $color;
       }

       public function getColor()
       {
           return($this->color);
       }

       public function getName()
       {
           return(parent::getName());
       }
   }

   $w1 = new Widget('Cog', 5.00);
   $w2 = new Thing('Cog', 5.00);
   $w2->setColor('Yellow');

   //TRUE (still!) 结果仍然为真
   if($w1->equals($w2))
   {
       print("w1 and w2 are the same\n");
   }

   //print Cog 输出 Cog
   print($w2->getName());
?＞