无法从子类访问父变量

Question

I want to reuse a few values from the parent class in the child class, but it seems that the child class cannot read the values that use the context $this in the parent method.

class Mother{

   public function __construct($field,$val){

       $this->field = $field;

       $this->val = $val;

   }

   public function set(){

        return array('val'=>$this->val,
                    'field'=>$this->field,
                    'test'=>"test");
   }

}

class Sister extends Mother{

   public function getVal(){

     $val = parent::set();

     print_r($val);

   }
}

The output would be

  Array ( [val] => [field] => [test] => test)

I have tried to turn the set() method static but that don't have anything to do with the problem. Can anyone tell me how to store the values in the parent class and pass it to the child class?

Answer 1

Your example will not print anything, because you don't call the class.

Try this

class Mother{

   public function __construct($field,$val){

       $this->field = $field;

       $this->val = $val;

   }

   public function set(){

        return array('val'=>$this->val,
                    'field'=>$this->field,
                    'test'=>"test");
   }

}

class Sister extends Mother{

   public function getVal(){

     $val = parent::set();

     return $val;

   }
}

$class = new Sister('test1', 'test2');

print_r($class->getVal());