Experiment on chained exceptions in Twisted

gistfile1.py

from twisted.internet.defer import Deferred

# presumably should do some sort of chaining like so
# http://stackoverflow.com/questions/1350671/inner-exception-with-traceback-in-python
# by using methods from twisted.python.failure.Failure
#
# there may also be better support for this in Twisted already :)

def err_handler(failure):
    failure.trap(OSError)
    print "Error", failure

def err_handler2(failure):
    print "Error #2", failure
    d = Deferred()
    d.errback(Exception(failure))
    return d

def err_handler3(failure):
    print "Error #3", failure

def stuck(value):
    print "Should not be here", value

d = Deferred()
d.addCallbacks(stuck, err_handler)
d.addErrback(err_handler2)
d.addErrback(err_handler3)
print d.errback(KeyError("wtf"))