Why can't you have require* statements in a class definition?

Possibly Related:
Why don't PHP attributes allow functions?

Pardon me if this has been asked before, but why can you not have something like the following:

class foo {

 require_once 'defines.php';

 private $_server = DB_SERVER;
 private $_username = DB_USERNAME;
 private $_password = DB_PASSWORD;
 private $_database = DB_NAME;
 public  $debug = false;
 public $_conn;

 function __construct() {                          
    $connection = @mysqli_connect($this->_server, $this->_username, $this->_password, $this->_database);
 }

 ...

}

Cheers,

EDIT: Looking to find out why this behaviour exists and why its not possible. Как так получилось, что голоса закрываются?

EDIT2 : Хотели бы также повторно открыть это