[Twisted-Python] lambdas and DeferredList

[gary jefferson]

I don't quite understand the behavior of lambdas in the following code:

from twisted.internet import reactor, defer

def someDeferred(val):
    d = defer.Deferred()
    reactor.callLater(1, d.callback, val)
    return d

def done(result):
    print "all done"
    reactor.stop()

def twothing(i):
    print "twothing: %s" % i
    return i

def onething(result, i, callableThing):
    print "onething: %s, result %s" % (i, result)
    callableThing()

def dlistspawn():
    dlist = []
    values = [(1, 'one'), (2, 'two'), (3, 'three')]
    for i, v in values:
        deferred = someDeferred(i)
        deferred.addCallback(onething, i, lambda: twothing(v))
        dlist.append(deferred)
    dl = defer.DeferredList(dlist)
    dl.addCallback(done)
    return dl

if __name__ == "__main__":
    dlistspawn()
    reactor.run()


Which produces:
onething: 1, result 1
twothing: three
onething: 2, result 2
twothing: three
onething: 3, result 3
twothing: three
all done


Why does the call to twothing() (via a lambda and callableThing)
always bind to 'three'?  How do I change the code to get it to bind
successively to 'one', 'two', and 'three'?

Thanks,
Gary