Python Twisted's inlineCallbacks decorator II

在此摘抄一个一般defer和defer.inlineCallbacks的用法比较的例子：

view sourceprint?from twisted.internet import reactor, defer

from twisted.web.client import getPage

import re



def lookup(country, search_term):

    main_d = defer.Deferred()



    def first_step():

        query = "%s/search?q=%s" % (country,search_term)

        d = getPage(query)

        d.addCallback(second_step, country)

        d.addErrback(failure, country)



    def second_step(content, country):

        m = re.search('http://[^"]+)"',

                      content, re.DOTALL)

        if not m:

            main_d.callback(None)

            return

        url = m.group('url')

        d = getPage(url)

        d.addCallback(third_step, country, url)

        d.addErrback(failure, country)



    def third_step(content, country, url):

        m = re.search("", content)

        if m:

            title = m.group(1)

            main_d.callback(dict(url = url, title = title))

        else:

            main_d.callback(dict(url=url, title="{not-specified}"))



    def failure(e, country):

        print ".%s FAILED: %s" % (country, str(e))

        main_d.callback(None)



    first_step()

    return main_d



def printResult(result, country):

    if result:

        print ".%s result: %s (%s)" % (country, result['url'], result['title'])

    else:

        print ".%s result: nothing found" % country



def runme():

    all = []

    for country in ["com", "pl", "nonexistant"]:

        d = lookup(country, "Twisted")

        d.addCallback(printResult, country)

        all.append(d)

    defer.DeferredList(all).addCallback(lambda _: reactor.stop())



reactor.callLater(0, runme)

reactor.run()

 

inlineCallbacks：

from twisted.internet import reactor, defer

from twisted.web.client import getPage

import re



@defer.inlineCallbacks

def lookup(country, search_term):

    try:

        query = "%s/search?q=%s" % (country,search_term)

        content = yield getPage(query)



        m = re.search('http://[^"]+)"',

                      content, re.DOTALL)

        if not m:

            defer.returnValue(None)



        url = m.group('url')

        content = yield getPage(url)



        m = re.search("", content)

        if m:

            defer.returnValue(dict(url=url, title=m.group(1)))

        else:

            defer.returnValue(dict(url=url, title="{not-specified}"))



    except Exception, e:

        print ".%s FAILED: %s" % (country, str(e))



def printResult(result, country):

    if result:

        print ".%s result: %s (%s)" % (country, result['url'], result['title'])

    else:

        print ".%s result: nothing found" % country



def runme():

    all = []

    for country in ["com", "pl", "nonexistant"]:

        d = lookup(country, "Twisted")

        d.addCallback(printResult, country)

        all.append(d)

    defer.DeferredList(all).addCallback(lambda _: reactor.stop())



reactor.callLater(0, runme)

reactor.run()