A logged_in? method is fairly common in rails authentication these days. We use it to determine if there *is* a logged-in user for layouts that are shared public and private - for example to use for greetings, login-only navigation features and displaying the correct login/logout buttons.
Once you've implemented CAS signup and a current_user method, you can use the very simple code below on your ApplicationHelper to get the logged_in? functionality
def logged_in? @current_user.present? end
Some authentication applications (eg restful_auth) will use a call to logged_in? as an opportunity to actually try to log a user in... but RubyCAS is more complicated than a simple cookie-login... so I've left actual authentication just to the filter-mechanisms already described.
If you have templates where - if you *can* login a user, you'd like to... but you'd like them also to be available to non-logged in users, then you'll need a Gateway filter.
This is one article in a series on Rails single-sign-on with rubyCAS