clean.php

<?php

// Class String
class String {
  // protected variable
  protected $_string;
  // public variable
  public $string;
  
  // Assign string to public variable
  public function __construct($string) {
    $this->string = $string;
  }
  // Assign string to protected variable
  public function setValue($string) {
    $this->_string = $string;
  }
  
  /**
   * get CleanUp object
   * @return \CleanUp
   */
  public function getCleanUp() {
    return new CleanUp($this);
  }
}

// Class CleanUp
class CleanUp extends String {
  protected $_object;
  public function __construct($object) {
    $this->_object = $object;
  }
  public function doAction() {
    // Clean this object
    $vars = get_object_vars($this->_object);
    return $vars;
  }
}

$stringObj = new String('Andy 123');
$stringObj->setValue('Andy protected');
print_r($stringObj->getCleanup()->doAction());