php 5 mysqli wrapper - error handler

// mysql error class
class MySqlError{

//
// private members
//

private $Server;
private $User;
private $Date;
private $Script;
private $Referrer;
private $Environment;

//
// public members
//

public $Database;
public $Message;
public $CommandText;
public $Parameters;

//
// constructor
//

public function __construct() {

 $this->Server = $_SERVER['SERVER_NAME'];
 $this->User = isset($_SESSION['user_id']) ? $_SESSION['user_id'] : '';
 $this->Date = date('Y-m-d H:i:s');
 $this->Script = 'http://' . $_SERVER['SERVER_NAME'] . $_SERVER['SCRIPT_NAME'] . '?' . $_SERVER['QUERY_STRING'];
 $this->Referrer = $_SERVER['HTTP_REFERER'];
 $this->Environment = $this->var_dump_ret($_REQUEST);
}

//
// private methods
//

// return var_dump as a string
private function var_dump_ret($mixed) {

 ob_start();
 var_dump($mixed);
 $content = ob_get_contents();
 ob_end_clean();
 return $content;
}

//
// public methods
//

// log error message to file and send email
public function Log() {

 $message = 'User: ' . $this->User . "\n"
 . 'Date: ' . $this->Date . "\n"
 . 'Script: ' . $this->Script . "\n"
 . 'Referrer: ' . $this->Referrer  . "\n\n"
 . 'Message: ' . $this->Message . "\n\n"
 . 'CommandText: ' . "\n" . $this->CommandText . "\n\n"
 . 'Parameters: ' . "\n" . $this->var_dump_ret($this->Parameters) . "\n"
 . 'Environment: ' . "\n" . $this->Environment;

 // append message to log file if it exists
 if($handle = fopen(SITE_DIR . 'logs/errors.txt','ab')){

  fwrite($handle, $message);
  fclose($handle);
 }

 // email message
 $oMail = new cMail();
 $oMail->from = 'you@domain.com';
 $oMail->addTo('you@domain.com');
 $oMail->subject = "Website Error";
 $oMail->message = $message;
 $oMail->send();
}

}
?>