Rendering from a filter class

I'm defining an around filter as its own class. The documentation on
ActionController::Filters::ClassMethods includes this example:

  class Authorizer
    # This will run before the action. Redirecting aborts the action.
    def before(controller)
      unless user.authorized?
        redirect_to(login_url)
      end
    end

    # This will run after the action if and only if before did not
render or redirect.
    def after(controller)
    end
  end

It also includes the explanatory text, "If before renders or
redirects, the filter chain is halted and after will not be run"
implying that these filters can render. What I'm not clear on is how.

In my class, calls to render result in a no such method error. I tried
calling controller.render, and it turns out that's protected. I can
get around this using send, but I doubt that's actually the right way.
Does anyone happen to know what the right way is?

The tests for this feature and the implementation of around_filters
use controller.__send__, so you'll likely need the same. The
documentation appears to be incorrect...

--Matt Jones