Dynamic Role Authorization in Rails using a database. Declarative Authorization the best choice?

I will need to provide dynamic role assignments (Roles/ Privileges) .More clearly, an end user should be able to create a role, assign permissions to a new user. So I was thinking of storing roles and privileges in a table for each user.

Is there a smart way to do this (any other plugin?),or or should I write code to do this with Declarative Authorization . Some light would help.Thanks!

Try answering these to get closer to a solution:

1. Are the roles themselves dynamic? i.e. Can the privileges assigned various to roles can be changed through the web interface by an Admin? If yes, then you should be storing this information into your database. For a system like a blog, where roles are pre-defined eg. Admin, Guest and Moderator, Declarative Authorization works like a charm.
2. How strong is the coupling of permissions to the UI? (Sometimes it just a couple of places you need to restrict, in other cases, like a social network, permissions are a lot more complex and coupled tightly with the UI). If its very tightly coupled, i.e. one action is available to all sorts of roles but the actions these roles perform are limited by their definition, then Declarative Authorization (or the likes) won't help much, you need a legacy system.