On my main Drupal site, users need to be able to select a display preference (e.g. 'high visibility'). This will be available to registered and anonymous users but only for their session, so I plan to store their preference in a session variable:
$_SESSION['display'] = $my_preference;
Another Drupal site runs on a subdomain of the main site, and needs the same functionality. And if the user visits both sites, it would be great to remember their preference.
I think that if I uncomment this line in both site's settings.php, session variables can be accessed across sites on the same domain?
$cookie_domain = 'maindomain.com';
So then I could set $_SESSION['display'] on one site, and retrieve $_SESSION['display'] on the other?
Also, one site is D6 and the other D7 - will this be a problem? Is caching for anonymous users going to cause problems?
Am I on the right lines, or is this plan flawed? Thanks