You can easily execute php into smarty templates using the {php} tag :
{if $smarty.get.id_category|intval}
{php}
global $cookie;
Configuration::get('PW_SORT_ENABLE');
{/php}
{/if}
To access PHP variables in {php} blocks, you will need to use the PHP global keyword.
Smarty cache is great for server performance on production but is annoying on developpement.
Hopefully, you can enable or disable it.
On prestashop 1.3.x or less, you have to edit the root/config/smarty.config.php and edit these 2 lines
$smarty->caching = false; // to pass "true" when put into production $smarty->force_compile = true; // to pass "false" when put into production
On prestashop 1.4.x or more, you can do it directly on the backoffice, preference tab, performences subtab
Sometimes you need to make a script usig the prestashop framework. To do that, just add these 2 lines at the top of your script
include(dirname(__FILE__).'/../../config/config.inc.php'); include_once(_PS_ROOT_DIR_.'/init.php');