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#!/usr/bin/env python
# Copyright (c) 2009 Twisted Matrix Laboratories.
# See LICENSE for details.
from twisted.internet import defer
from twisted.python import failure, util
"""
Here we have the simplest case, a single callback and a single errback.
"""
num = 0
def handleFailure(f):
print "errback"
print "we got an exception: %s" % (f.getTraceback(),)
f.trap(RuntimeError)
def handleResult(result):
global num; num += 1
print "callback %s" % (num,)
print "\tgot result: %s" % (result,)
return "yay! handleResult was successful!"
def behindTheScenes(result):
# equivalent to d.callback(result)
if not isinstance(result, failure.Failure): # ---- callback
try:
result = handleResult(result)
except:
result = failure.Failure()
else: # ---- errback
pass
if not isinstance(result, failure.Failure): # ---- callback
pass
else: # ---- errback
try:
result = handleFailure(result)
except:
result = failure.Failure()
def deferredExample():
d = defer.Deferred()
d.addCallback(handleResult)
d.addErrback(handleFailure)
d.callback("success")
if __name__ == '__main__':
behindTheScenes("success")
print "\n-------------------------------------------------\n"
global num; num = 0
deferredExample()
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