Question

I have lot of code in my Tornado app which looks like this:

@tornado.web.asynchronous
def get(self):
    ...
    some_async_call(..., callback=self._step1)

def _step1(self, response):
    ...
    some_async_call(..., callback=self._step2)

def _step2(self, response):
    ...
    some_async_call(..., callback=self._finish_request)


def _finish_request(self, response):
    ...
    self.write(something)
    self.finish()

Obviously inline callbacks would simplify that code a lot, it would look something like:

@inlineCallbacks
@tornado.web.asynchronous
def get(self):
    ...
    response = yield some_async_call(...)
    ...
    response = yield some_async_call(...)
    ...
    response = yield some_async_call(...)
    ...
    self.write(something)
    self.finish()

Is there a way of having inline callbacks or otherwise simplifying the code in Tornado?

Answer 1

Found it. In Tornado it’s not called inline callbacks, but rather “a generator-based interface” — tornado.gen. Thus my code should look something like:

@tornado.web.asynchronous
@gen.engine
def get(self):
    ...
    response = yield gen.Task(some_async_call(...))
    ...
    response = yield gen.Task(some_async_call(...))
    ...
    response = yield gen.Task(some_async_call(...))
    ...
    self.write(something)
    self.finish()