我使用一个if
-语句来决定是否触发一个Deferred
。不过,它在检查运行之前就已经启动了。从输出来看,Deferred
在运行reactor.run()
时立即启动。不一定要触发回调才能发生这种情况吗?你知道吗
相关代码段:
class OutpostBurrowNew(amp.AMP, Protocol):
protocol = OutpostGopher
...
def rfidTest(self):
print('Checking for tag - Deferred called: %s' % str(self.defer.called))
(status,TagType) = MIFAREReader.MFRC522_Request(MIFAREReader.PICC_REQIDL)
if status == MIFAREReader.MI_OK:
status,uid = self.verify_card()
cardid = '-'.join([str(x) for x in uid])
print('Card detected: %s' % str(cardid))
self.defer.callback()
def main3():
''' main3() is for testing reactor usage of RFID-card reading '''
burrow = OutpostBurrowNew('client')
burrow.protocol = OutpostGopher
burrow.connectEndpoint() # A deferred is created, set on burrow.defer
def printerCallback(proto):
# This gets passed the OutpostGopher protocol
print('main3.printerCallback() - %s ' % str(time.time()))
burrow.defer.addCallback(printerCallback)
looper = LoopingCall(burrow.rfidTest)
loopdefer = looper.start(1, now=False)
print('Deferred just created, status: %s' % str(burrow.defer.called))
reactor.run()
输出:
(env)pi@raspi ~/zenithproject/zenith $ sudo python indev/rfidread_remote.py
Deferred just created, status: False
Gopher.connectionMade() called.
main3.printerCallback() - 1426884127.26
Checking tag - Deferred called: True
Checking tag - Deferred called: True
Checking tag - Deferred called: True
^CCtrl+C captured, ending read.
我发现当一个扭曲的端点(在本例中是
TCP4ClientEndpoint
)连接到另一个端点(这里是TCP4ServerEndpoint
)时,由该连接创建的Deferred
会立即被触发(即连接时自动调用Protocol.connectionMade()
)。你知道吗这是通过在
Deferred
需要被激发之前不建立连接来解决的(或者,我想我可以创建另一个Deferred
来使用),如下所示:结果如下:
注意输出:
回到
main
,我们看到printerCallback是burrow.defer
的回调。我们知道它正在运行,因为它的输出是打印出来的。所以你应该找出谁在叫它。一种方法是在printerCallback中引发异常,即如果需要更具体地使用跟踪,可以使用inspect模块。你知道吗
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