quick done new hook in a module

<?php
// quick done example for creating a new hook in PrestaShop 1.4.x
// /!\ Not tested,

class Mymodule extends Module {
    public function install(){
        // let's create the hook (if it not exists)
        $hook = new Hook();
        $hook->name = 'top_menu';
        $res = $hook->save();
        // return true on install succeed
        if ($res && parent::install())
            return true;
        return false;
    }
    public function uninstall()
    {
        // uninstall the module will uninstall the hook :)
        $hook = Hook::get('top_menu');
        $res = $hook->delete();
        // return true on uninstall succeed
        if ($res && parent::uninstall())
            return true;
        return false;
    }
    public function hookTop_Menu(){
        // of course, your theme contains {$TOP_MENU} somewhere !

        // feel free to execute any code here
        $a = 1;$b = 2; $c = $a + $b;

        global $smarty;
        // (you can use smarty)
        $smarty->assign('res', $c);

        // or also simple echos (not recommended of course)
        echo "this will be displayed on pages containing {$TOP_MENU} (if I have good memories)";
    }
}
?>