twisted_main.py

"""
Run this example with:
 python -m github.twisted_main

This is an example of using Effect with Twisted.

It's important to note that none of the application code relies on Twisted --
this is the only file that has any dependencies on Twisted. There's also an
example of running the same application code in ``sync_main.py`` in the same
directory.

This code has these responsibilities:

- set up a dispatcher that knows how to find performers for all intents
 used in this application. The application uses ReadLine, HTTPRequest, and
 ParallelEffects.
- use :func:`texeffect.perform` to perform an effect, which returns a
 Deferred that we can return from our react function.
"""

from __future__ import print_function

from twisted.internet.task import react

from txeffect import make_twisted_dispatcher, perform
from effect import ComposedDispatcher, TypeDispatcher

from ehttp.http_intent import HTTPRequest
from ehttp.twisted_http import perform_request_with_treq
from readline_intent import ReadLine, perform_readline_stdin

from .core import main_effect


def get_dispatcher(reactor):
 """
 Create a dispatcher that can find performers for :obj:`ReadLine`,
 :obj:`HTTPRequest`, and :obj:`ParallelEffects`.
 :func:`make_twisted_dispatcher` is able to provide the ``ParallelEffects``
 performer, so we compose it with our own custom :obj:`TypeDispatcher`.
 """
 return ComposedDispatcher(
 [
 TypeDispatcher(
 {
 ReadLine: perform_readline_stdin,
 HTTPRequest: perform_request_with_treq,
 }
 ),
 make_twisted_dispatcher(reactor),
 ]
 )


def main(reactor):
 dispatcher = get_dispatcher(reactor)
 eff = main_effect()
 return perform(dispatcher, eff).addCallback(print)


if __name__ == "__main__":
 react(main, [])