<?php

class A {
  var $a;
  var $b;
  var $c;
  var $d;
  public function __construct($p1, $p2, $p3, $p4) {
    $this->a = $p1;
    $this->b = $p2;
    $this->c = $p3;
    $this->d = $p4;
  }
}
;
$obj = new A(1, 2, 3, 4);
foreach ($obj as $key => &$val) {
  if($val == 2) {
    $obj->$key = 0;
  }
 else if($val == 3) {
    var_dump($key);
    unset($obj->$key);
  }
 else {
    $val++;
  }
}
var_dump($obj);
