爬虫日记(100)：Twisted:使用Deferred重构回调函数管理

Posted 2021-08-23 caimouse

前面的例子可以看到下载诗歌的例子里，使用回调函数来进行实现客户端的代码，这样需要传送两上回调函数进去，接着下来我们使用已经学习的Deferred类来管理回调函数，就不必要传送回调函数了，这样让代码更加简单，并且容易管理。

例子如下：

# This is the Twisted Get Poetry Now! client, version 4.0

import optparse, sys

from twisted.internet import defer
from twisted.internet.protocol import Protocol, ClientFactory


def parse_args():
    usage = """usage: %prog [options] [hostname]:port ...

This is the Get Poetry Now! client, Twisted version 4.0
Run it like this:

  python get-poetry.py port1 port2 port3 ...

If you are in the base directory of the twisted-intro package,
you could run it like this:

  python twisted-client-4/get-poetry.py 10001 10002 10003

to grab poetry from servers on ports 10001, 10002, and 10003.

Of course, there need to be servers listening on those ports
for that to work.