abstract class DataKeeper {
  protected $data;

  public function setData($data) {
    $this->data = $data;
  }

  public function getData() {
    return $this->data;
  }

  abstract public function save()
  
  abstract public function process()
}

class FileDataKeeper extend DataKeeper {

  public function save() {
    // implementation
  }

  public function process() {
    // implementation
  }
}

class Container {
  protected static $classes = array();  

  public static function register($alias, $class) {
    self::$classes[$alias] = $class;    
  }

  public static function get($alias) {
    if (!isset(self::$classes[$alias]))
	throw new Exception("...");      

    $className = self::$classes[$alias];
    return new $className();
  }
}


// bootstrap.php
Container:register("dataKeeper", "FileDataKeeper");

// SomeWhere.php
$dataKeeper = Container::get("dataKeeper");

public function beforeSave() {
  if ($this->isNewRecord)
     $this->password = md5($this->password);
  return parent::beforeSave();
}

var nativePrompt = prompt;
var prompt = function(msg) {
    return nativePrompt(msg) || '';
}

console.log(prompt('Username:').toLowerCase())