Use Twisted Anywhere!¶

Crochet is an MIT-licensed library that makes it easier for blocking and threaded applications like Flask or Django to use the Twisted networking framework.

Here’s an example of a program using Crochet. Notice that you get a completely blocking interface to Twisted and do not need to run the Twisted reactor, the event loop, yourself.

#!/usr/bin/python
"""
Do a DNS lookup using Twisted's APIs.
"""
from __future__ import print_function

# The Twisted code we'll be using:
from twisted.names import client

from crochet import setup, wait_for
setup()


# Crochet layer, wrapping Twisted's DNS library in a blocking call.
@wait_for(timeout=5.0)
def gethostbyname(name):
    """Lookup the IP of a given hostname.

    Unlike socket.gethostbyname() which can take an arbitrary amount of time
    to finish, this function will raise crochet.TimeoutError if more than 5
    seconds elapse without an answer being received.
    """
    d = client.lookupAddress(name)
    d.addCallback(lambda result: result[0][0].payload.dottedQuad())
    return d


if __name__ == '__main__':
    # Application code using the public API - notice it works in a normal
    # blocking manner, with no event loop visible:
    import sys
    name = sys.argv[1]
    ip = gethostbyname(name)
    print(name, "->", ip)

Run on the command line:

$ python blockingdns.py twistedmatrix.com
twistedmatrix.com -> 66.35.39.66

Use Twisted Anywhere!¶

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