Is there a way to implement a deferred sequence?
Greetings. I want a sequence which is Deferred with two callbacks: one as usual - for the whole result called at the end of the sequence, another - called for every element of the sequence (as they arrive). The number of elements is not known beforehand, so it is not a defer.DeferredList, but the idea is almost the same. To provide some interface to send items to the sequence, fire item callback for every item arrived and have main callback to be called at the end of the sequence. It could be used for example in AJAX web-applications that use Athena to simplify/automate the dynamic updates of some slowly arriving results (while in AJAX-supporting environment) and to gracefully fallback when javascript is not enabled/not desired. It could be deployed as using a slightly modified "sequence"-like renderer with "data" function returning this form of Deferred. The renderer will output some 'live' element immediately and then will append remotely it's contents as items arrive. Or will fallback to the usual builtin "sequence" renderer when AJAX is not desired. I think this approach will make it possible to hide all details into the renderer code. The same could be done to make items replace each other with the last being displayed as the final result... Or maybe it is already done in a different way? Or have I missed something, could anyone point me, please? Thanks for your time. -- Alexey S.
Alexey, I thought you could use Trellis. On Thu, Apr 9, 2009 at 6:30 PM, <twisted-web@udmvt.ru> wrote:
Greetings.
I want a sequence which is Deferred with two callbacks: one as usual - for the whole result called at the end of the sequence, another - called for every element of the sequence (as they arrive).
The number of elements is not known beforehand, so it is not a defer.DeferredList, but the idea is almost the same. To provide some interface to send items to the sequence, fire item callback for every item arrived and have main callback to be called at the end of the sequence.
It could be used for example in AJAX web-applications that use Athena to simplify/automate the dynamic updates of some slowly arriving results (while in AJAX-supporting environment) and to gracefully fallback when javascript is not enabled/not desired.
It could be deployed as using a slightly modified "sequence"-like renderer with "data" function returning this form of Deferred. The renderer will output some 'live' element immediately and then will append remotely it's contents as items arrive. Or will fallback to the usual builtin "sequence" renderer when AJAX is not desired.
I think this approach will make it possible to hide all details into the renderer code.
The same could be done to make items replace each other with the last being displayed as the final result...
Or maybe it is already done in a different way? Or have I missed something, could anyone point me, please?
Thanks for your time.
-- Alexey S.
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