Access variables in antother Lua state

[Marc Balmer <marc@...>]

Our webapplications at the moment use Lua to prepare data to be sent to
the browser and ClearSilver to render webpages, i.e. to mix the data and
the template.

Now we wrote a new templating system (we call it Lua Templates) which
could one day replace ClearSilver in our products.  For security reasons
we do not want to run the template renderer in the same Lua state we do
the data preparation in.  Is there a way to access objects from one
state in another state?  Something like proxy tables, that behave like
normal tables, but actually are store in different state?

The idea is to have the template engine to run in a sandbox of its own,
preventing access to data and methods the data processing state uses
(like e.g. DB connections etc.)

Any ideas?