Web application templating system for Python and Twisted

 Nevow's main focus is on separating the HTML template from both the
 business logic and the display logic, while allowing the programmer
 to write pure Python code as much as possible. It separates your code
 into 'data' and 'render' functions, a simplified implementation of
 traditional MVC. It has various parts which can be used individually
 or as a whole, integrated web solution:
 .
  - XHTML templates: contain no programming logic, only nodes tagged
    with nevow attributes
  - data/render methods: simplified MVC
  - stan: An s-expression-like syntax for expressing xml in pure Python
  - formless: For describing the types of objects which may be passed
    to methods of your classes, validating and coercing string input from
    either web or command-line sources, and calling your methods
    automatically once validation passes
  - freeform: For rendering web forms based on formless type
    descriptions, accepting form posts and passing them to formless
    validators, and rendering error forms in the event validation fails
  - livepage: Cross-browser JavaScript glue for sending client side
    events to the server and server side events to the client after the
    page has loaded, without causing the entire page to refresh