Using Python metaclass to create a metaclass factory that decorates all tornado handler methods with tornado.web.authenticated when a handler inherits from AuthenticatedHandler.

AlwaysAuthenticatedHandler.py

import tornado.web

class BaseHandler(tornado.web.RequestHandler):
    pass

def MetaClassFactory(function):
    class MetaClass(type):
        def __new__(meta, classname, bases, classDict):
            newClassDict = {}

            supported_methods = ("GET", "HEAD", "POST", "DELETE", "PATCH",
                                 "PUT", "OPTIONS")
            for method_name in [m.lower() for m in supported_methods]:
                if method_name not in classDict:
                    continue

                method = classDict[method_name]
                newMethod = function(method)

                newClassDict[method_name] = newMethod
            return  type.__new__(meta, classname, bases, newClassDict)
    return MetaClass

AlwaysAuthenticated = MetaClassFactory(tornado.web.authenticated)

class AuthenticatedHandler(BaseHandler):

    __metaclass__ = AlwaysAuthenticated

    def head(self, *args, **kwargs):
        raise HTTPError(405)

    def get(self, *args, **kwargs):
        raise HTTPError(405)

    def post(self, *args, **kwargs):
        raise HTTPError(405)

    def delete(self, *args, **kwargs):
        raise HTTPError(405)

    def patch(self, *args, **kwargs):
        raise HTTPError(405)

    def put(self, *args, **kwargs):
        raise HTTPError(405)

    def options(self, *args, **kwargs):
        raise HTTPError(405)

class NotAuthenticatedHandler(BaseHandler):

    def head(self, *args, **kwargs):
        raise HTTPError(405)

    def get(self, *args, **kwargs):
        raise HTTPError(405)

    def post(self, *args, **kwargs):
        raise HTTPError(405)

    def delete(self, *args, **kwargs):
        raise HTTPError(405)

    def patch(self, *args, **kwargs):
        raise HTTPError(405)

    def put(self, *args, **kwargs):
        raise HTTPError(405)

    def options(self, *args, **kwargs):
        raise HTTPError(405)

class SomeHandler(NotAuthenticatedHandler):
    def get(self):
        self.render("index.html", user=self.current_user)

class SomeOtherHandler(AuthenticatedHandler):
    def get(self):
        self.render("other.html", user=self.current_user)

# ...