public function getAll()
 {
     $conexion = new Conexion();
     $consulta = $conexion->prepare('SELECT * FROM ' . self::TABLA);
     $consulta->execute();
     while ($registro = $consulta->fetch()) {
         $rol = new Rol();
         $rol->construir($registro);
         $array[] = $rol;
     }
     return $array;
 }