On 02/11/11 12:39, Itamar Turner-Trauring wrote:
> On Wed, 2011-11-02 at 11:24 +0000, Phil Mayers wrote:
>> I only just noticed today that if a generator passed to a
>> CooperativeTask does:
>>
>> result = yield some_deferred()
>>
>> ...it doesn't work, because CooperativeTask doesn't .send() the result
>> of the deferred bacn into the generator.
>>
>> Is this intentional? If not, would that behaviour be desirable? It seems
>> like it would be a useful pattern to me.
>
> Could you give an example snippet? I don't really understand the
> question, sorry.
I meant this:
from twisted.internet import task, reactor, defer
def dowork(n):
d = defer.Deferred()
result = 'waited %i' % (n,)
reactor.callLater(n, d.callback, result)
return d
def work():
for i in (1,2,3):
rv = yield dowork(i)
print rv
task.coiterate(work())
reactor.run()
...prints:
None
None
None
rather than
waited 1
waited 2
waited 3
i.e. the iterator that is yielding deferreds doesn't "see" the results
emerge from the "yield" in the same way inlineCallbacks do.
Obviously it's pretty trivial to get at the results:
holder = {}
def cb(r):
holder['result'] = r
return r
yield dowork(i).addCallback(cb)
print holder['result']
But the essential point I was missing is that Cooperator is for general
purpose iterators, not just generators.
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