<?php
class UserInfo{
  private $username;
  private $privileges;

  public function __get($property) {
    if (property_exists($this, $property)) {
      return $this->$property;
    }
  }

  public function __set($property, $value) {
    if (property_exists($this, $property)) {
      $this->$property = $value;
    }

    return $this;
  }
}

$user=new UserInfo;
$user->__set($username,"someuser");
echo $user->__get($username);
?>