php OOP parent to child relationship

Question

class base{
 public $c = 'c';
 public $sub  = '';
 function __construct(){
    $this->sub = new sub();
 }
}

class sub extends base{
 public $ab = 'abs';
 function __construct(){
  $this->c = 'aas';
  echo 'Test';
 }
}


$a = new base();
print_r($a);

I would like to the sub class to edit the base vars $this->c = 'blabla';

how can i achieve this?

Answer 1

't wouldn't be code I was proud of (different constructor signatures), but this would work (single use):

class base{
 public $c = 'c';
 public $sub  = '';
 function __construct(){
    $this->sub = new sub($this);
 }
}

class sub extends base{
 public $ab = 'abs';
 function __construct($parent){
  $parent->c = 'aas';
  echo 'Test';
 }
}

If you need it more often:

class base{
 private $parent;
 private $top;
 public $c = 'c';
 public $sub  = '';
 function __construct(base $parent = null, base $top = null){
    $this->parent = $parent;
    $this->top    = $top;
    $this->addSub();
 }
 function addSub(){
    $this->sub    = new sub($this,$this->top ? $this->top : $this);
 }

}

class sub extends base{
 public $ab = 'abs';
 function __construct($parent,$top){
  parent::__construct($parent,$top);
  $this->parent->c = 'aas';
 }
 function foo($bar){
    $this->top->c = $bar;
 }
 //preventing infinite recursion....
 function addSub(){
 }
}

Depending on what the actual needs are, another design pattern is likely more suited.

Answer 2

Why not just override it:

class sub extends base
{
    public $ab = 'abs';
    public $c = 'blabla';
}

Otherwise, if you need to modify the actual base property, use parent as Wrikken suggested.