which is better ?

app.py

#!/usr/bin/env python
#coding=utf-8

import tornado.web
import tornado.ioloop
import tornado.autoreload

from controllers import Users

App         = tornado.web.Application
Asynchronous= tornado.web.asynchronous
Server      = tornado.ioloop.IOLoop.instance()

app = App([

    (r'/user/login', Users.login ),
])

app.listen(8888)
tornado.autoreload.start(Server)
Server.start() 

Users.py (in controllers)

#!/usr/bin/env python
#coding=utf-8

import tornado.web

from baseController import BaseController
from models import user

class login(BaseController):

    @tornado.web.asynchronous
    def post(self):

        users = user.User()  # is use like this OK ?
        users.login(self.response)

    def response(self, ret):

        self.finish(ret)

user.py ( in models)

#!/usr/bin/env python
#coding=utf-8

import copy

from baseModle import BaseModle

class User(BaseModle):

    def login(self, callback):

        data = do something
        callback(data)

Users.py (in controllers) v2

#!/usr/bin/env python
#coding=utf-8

import tornado.web

from baseController import BaseController
from models import user

users = user.User()

class login(BaseController):

    @tornado.web.asynchronous
    def post(self):

       users.login(self.response)

    def response(self, ret):

        self.finish(ret)

---

上方那个方案更好。