Can i check userlogin in construct ?

PHP Code:

class Admin extends CI_Controller {
function __construct()
{
    parent::__construct();
       $aut = $this->donaturlib->is_admin();
    if(!$aut)
    {
$msg="Mohon Maaf anda tidak memiliki akses";
$this->session->set_flashdata('donatur',$msg);
redirect('welcome');
    }
    $this->link ='login/out';
$this->info ='Logout';
}
function index()
{
$data['link']=$this->link;
$data['info']=$this->info;
$data['include']= 'default';
$this->load->view('a_template/main.php',$data);    
}
} 


Up there is my script, i'm trying to check the user login in function __construct. It's working fine, but is it 'in the right way'?