在另一个之前处理一个功能

I'm creating very simple e-commerce platform and i'm stuck on meta tags. I have something like this (the code is very simplified of course :P):

class Blabla {

    public $meta_title = 'zzzzzzz';

    function pages() {
        $this->meta_title = 'xxxxxx';
    }

    function title() {
        return $this->meta_title;
    }
}

Than i have index.php like this:

require_once('blabla.php');
$blabla= new Blabla();
<html>
    (...)
    <?php echo $blabla->title(); ?>
    (...)
    <?php echo $blabla->pages(); ?>
    (...)
</html>

My question is how to run pages() first and display meta() correctly? I can add $this->pages() to __construct() but i think it's not the best way to solve my problem.