在子方法中访问父变量

Question

I currently have two classes, one called Dog, one called Poodle. Now how can I use a variable defined in Dog from the Poodle class. My code is as follows:

  class dog {
       protected static $name = '';

       function __construct($name) {
            $this->name = $name
       }
  }

  class Poodle extends dog {
       function __construct($name) {
           parent::__construct($name)
       } 

       function getName(){
           return parent::$name;
       }
  }

$poodle = new Poodle("Benjy");
print $poodle->getName();

I get this error

Notice: Undefined variable: name

Answer 1

i guess 'name' is an attribute of the concrete Dog, so it shouldn't be static in the first place. To access non-static parent class attributes from within an inherited class, just use "$this".

    class dog {
       protected $name = '';

       function __construct($name) {
            $this->name = $name;
       }
    }

    class Poodle extends dog {
       function getName(){
           return $this->name;
       }
    }

Answer 2

The problem is in your Dog constructor. You wrote:

$this->name = $name;

But using $this implies that name is an instance variable, when in fact it's a static variable. Change it to this:

self::$name = $name;

That should work fine.

Answer 3

In your dog class you have declared the variable $name as static , you have to declare the variable without the static word

class dog {
   protected $name = '';

   function __construct($name) {
        $this->name = $name
   }
}



class Poodle extends dog {
   function __construct($name) {
       parent::__construct($name)
   } 

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

$poodle = new Poodle("Benjy");
print $poodle->getName();