'The authenticated user for this request.
This is set in one of two ways:
* A subclass may override `get_current_user()`, which will be called
automatically the first time ``self.current_user`` is accessed.
`get_current_user()` will only be called once per request,
and is cached for future access::
def get_current_user(self):
user_cookie = self.get_secure_cookie("user")
if user_cookie:
return json.loads(user_cookie)
return None
* It may be set as a normal variable, typically from an overridden
`prepare()`::
@gen.coroutine
def prepare(self):
user_id_cookie = self.get_secure_cookie("user_id")
if user_id_cookie:
self.current_user = yield load_user(user_id_cookie)
Note that `prepare()` may be a coroutine while `get_current_user()`
may not, so the latter form is necessary if loading the user requires
asynchronous operations.
The user object may be any type of the application\'s choosing.'

@property
def current_user(self):

    if (not hasattr(self, '_current_user')):
        self._current_user = self.get_current_user()
    return self._current_user
