Scheme/Design Pattern for allowing a certain outside class to set properties

I came up with a solution (in PHP) to a problem and am wondering if it is a named Design Pattern, and if it is good practice.

I have a collection class and an item class. The collection class is the only one allowed to set the item class's protected data, besides the class itself.

I did that by giving the item class a method that takes the collection object as an argument. The item object then sets its data with the collection objects.

That way, we can say:

$item_coll = new collection();
$item_coll->load($criterion1, $criterion2);

And now there is a collection of `item` objects with all their data set.



class item {
  protected $prop1;
  protected $prop2;

  public function setData(collection $coll, $id) {
    $data = $coll->getData($id);
    foreach($data as $key=>$value) {
      $this->$key = $value
    }
    return $this;
  }
}

class collection {
    protected $data = array();
    public function getData($id) {
      if(array_key_exists($id,$this->data) ) {
        return $this->data[$id];
      } else return array();
    }
    public function load(someClass $obj1, someClass2 $obj2) { // arguments not relevant here, they determine the contents of the collection
      // based on arguments, data is loaded from database into $this->data;
      foreach($rows as $row) { // database data
        $this->data[$id] = $row;
        $obj = $this->collection[$id] = new item();
        $obj->setData($this,$id); // collection object passes itself into item object
      }
    }
}