python webapp2 framework , def func_name(handler):

Question

For which purpose handler class used:

example:

def user_required(handler):
  """
    Decorator that checks if there's a user associated with the current session.
    Will also fail if there's no session present.
  """
  def check_login(self, *args, **kwargs):
    auth = self.auth
    if not auth.get_user_by_session():
      self.redirect(self.uri_for('login'), abort=True)
    else:
      return handler(self, *args, **kwargs)

  return check_login

actually it is from this tutorial :

Answer 1

Example you mention is used as decorator. Handler is a method passed to a decorator to be decorated. This decorator is later user in class AuthenticatedHandler(BaseHandler):.

Roughly, in your example, get method is decorated by user_required, thus to understand what's going on just replace handler with get