Rails - Jul 2006 - Dynamically setting the session domain?

Does anyone know a way to dynamically change the session_domain option
of ActionController::CgiRequest?  I want to have a login section on an
index page (www.example.com) that takes a subdomain, username,
password, authenticates, then redirects to
http://#{subdomain}.mysite.com.

I need to set the session_domain option (to the subdomain) dynamically
so the cookie can be read when the user arrives after the redirect.  I
know I could do
ActionController::CgiRequest::DEFAULT_SESSION_OPTIONS.update(
:session_domain => ''example.com'') if I wanted to share
sessions across
domains, but I do not want to do this as I want to allow users to be
logged on to multiple subdomains at the same time.

Any ideas?

Thanks,
Zack

I just realized that 37Signal''s Backpack does exactly what I described
below.  Any ideas on how this is done?

Thanks,
Zack

On 7/11/06, Zack Chandler <zackchandler@gmail.com>
wrote:
> Does anyone know a way to dynamically change the session_domain option
> of ActionController::CgiRequest?  I want to have a login section on an
> index page (www.example.com) that takes a subdomain, username,
> password, authenticates, then redirects to
> http://#{subdomain}.mysite.com.
>
> I need to set the session_domain option (to the subdomain) dynamically
> so the cookie can be read when the user arrives after the redirect.  I
> know I could do
> ActionController::CgiRequest::DEFAULT_SESSION_OPTIONS.update(
> :session_domain => ''example.com'') if I wanted to share
sessions across
> domains, but I do not want to do this as I want to allow users to be
> logged on to multiple subdomains at the same time.
>
> Any ideas?
>
> Thanks,
> Zack
>