PHP Accessing Parent Class Variable

Question

class A {     private $aa;     protected $bb = 'parent bb';      function __construct($arg) {        //do something..     }      private function parentmethod($arg2) {        //do something..     } }  class B extends A {     function __construct($arg) {         parent::__construct($arg);     }     function childfunction() {         echo parent::$bb; //Fatal error: Undefined class constant 'bb'      } }  $test = new B($some); $test->childfunction(); 

Question: How do I display parent variable in child? expected result will echo 'parent bb'

Answer 1

echo $this->bb; 

The variable is inherited and is not private, so it is a part of the current object.

---

Here is additional information in response to your request for more information about using parent:::

Use parent:: when you want add extra functionality to a method from the parent class. For example, imagine an Airplane class:

class Airplane {     private $pilot;      public function __construct( $pilot ) {         $this->pilot = $pilot;     } } 

Now suppose we want to create a new type of Airplane that also has a navigator. You can extend the __construct() method to add the new functionality, but still make use of the functionality offered by the parent:

class Bomber extends Airplane {     private $navigator;      public function __construct( $pilot, $navigator ) {         $this->navigator = $navigator;          parent::__construct( $pilot ); // Assigns $pilot to $this->pilot     } } 

In this way, you can follow the DRY principle of development but still provide all of the functionality you desire.