jak zpřístupnit podtřídu

<?php
class View_class{
public $ms;
 function __contruct(){
 $this->ms=new View_messages_class();
 }
}

class View_messages_class{
private $numbers, $from_ids, $names, $ids, $subjects, $reads, $sentTimes, $colors;
 function __contruct(){
 $this->numbers=array(); $this->from_ids=array(); $this->names=array(); $this->ids=array(); $this->subjects=array(); $this->reads=array(); $this->sentTimes=array(); $this->colors=array();
 }
 public function addNumber(&$a){$this->numbers=$a;}
 public function addFrom(&$a){$this->from_ids=$a;}
 public function addName(&$a){$this->names=$a;}
 public function addID(&$a){$this->ids=$a;}
 public function addSubject(&$a){$this->subjects=$a;}
 public function addRead(&$a){$this->reads=$a;}
 public function addSent(&$a){$this->sentTimes=$a;}
 public function addColor(&$a){$this->colors=$a;}

 public function getNumbers(){return $this->numbers;}
 public function getFrom(){return $this->from_ids;}
 public function getNames(){return $this->names;}
 public function getIDs(){return $this->ids;}
 public function getSubjects(){return $this->subjects;}
 public function getRead(){return $this->reads;}
 public function getSent(){return $this->sentTimes;}
 public function getColors(){return $this->colors;}
}
$view=new View_class;
var_dump($view);
?>

object(View_class)#9 (1) {
  ["ms"]=>
  NULL
}