Question

有人可以解释以下之间的区别吗。我真的很难掌握延迟概念，我以为我已经拥有它，因为我整天都在做例子。但我认为我必须是盲目的代码。我确信它非常简单。

这很有效。

from twisted.spread import pb
from twisted.internet import reactor
from twisted.python import util


if __name__ == '__main__':

    def print_result(result):
        print result

    def add_numbers(obj, a, b):
        obj.callRemote("add_numbers", a, b)



    factory = pb.PBClientFactory()
    reactor.connectTCP("localhost", 8789, factory)
    d = factory.getRootObject()
    d.addCallback(lambda object: object.callRemote("add_numbers", 1, 2))
    d.addErrback(lambda reason: 'error: '+str(reason.value))
    d.addCallback(print_result)
    d.addErrback(lambda reason: 'error: '+str(reason.value))
    d.addCallback(lambda _: reactor.stop())
    d = factory.getRootObject()

    reactor.run()

这不是

from twisted.spread import pb
from twisted.internet import reactor
from twisted.python import util


if __name__ == '__main__':

    def print_result(result):
        print result

    def add_numbers(obj, a, b):
        obj.callRemote("add_numbers", a, b)



    factory = pb.PBClientFactory()
    reactor.connectTCP("localhost", 8789, factory)
    d = factory.getRootObject()
    d.addCallback(add_numbers, 1, 2)
    d.addErrback(lambda reason: 'error: '+str(reason.value))
    d.addCallback(print_result)
    d.addErrback(lambda reason: 'error: '+str(reason.value))
    d.addCallback(lambda _: reactor.stop())
    d = factory.getRootObject()

    reactor.run()

我不能为我的生活解决原因，它崩溃了这个错误：

Unhandled error in Deferred:
Unhandled Error
Traceback (most recent call last):
Failure: twisted.spread.pb.PBConnectionLost: [Failure instance: Traceback (failure  with no frames): <class 'twisted.internet.error.ConnectionLost'>: Connection to the other side was lost in a non-clean fashion: Connection lost.
]

服务器端代码是

from twisted.spread import pb
from twisted.internet import reactor

class Echoer(pb.Root):
    def remote_echo(self, st):
        print 'echoing:', st
        return st

    def remote_add_numbers(self, a, b):
        print 'adding:', a, b
        c = a + b
        return c

if __name__ == '__main__':
    reactor.listenTCP(8789, pb.PBServerFactory(Echoer()))
    reactor.run()

Answer 1

您的工作和损坏示例之间的区别在于lambda表达式隐式返回其结果。它的结果是Deferred，这意味着链中的下一个回调将等待执行，直到其结果可用。

如果您更改add_numbers的定义以返回callRemote的结果，请执行以下操作：

def add_numbers(obj, a, b):
    return obj.callRemote("add_numbers", a, b)

然后你破碎的例子将重新开始工作。

挣扎着理解Twisted，特别是pb

1 个答案: