[Twisted-Python] Re: Resource.render() returning NOT_DONE_YET
bob at redivi.com
Mon Apr 28 18:14:57 EDT 2003
On Monday, Apr 28, 2003, at 15:57 America/New_York, Glyph Lefkowitz
>> | 2. Alternatively, allow a Deferred to be a return
>> | value. Then the underlying caller can add
>> | result.finish() to the deferred chain. This
>> | has the advantage of not requiring finish() to
>> | really be managed. Either the return value is
>> | a string, a Deferred, (or for backwards compatibiliy
>> | NOT_DONE_YET). In either of the primary cases,
>> | result.finish() always gets called... thus making
>> | it easier on newbies.
> I've discussed this with several different people at various times...
> the trouble is, there isn't really a use-case that Deferreds make
> easier. render() ends up being a relatively low-level interface, and
> the NOT_DONE_YET/write/finish API is quite convenient for the stuff
> that has been implemented with it.
> I am definitely a True Believer in the Deferred, but in this case it
> just doesn't seem worth the inconvenience of deprecating things and
> shuffling stuff around for a vanishingly small benefit.
The error handling inherent with Deferred makes it worth it IMHO. I
see a lot of NOT_DONE_YET responses fail and it just hangs for the web
user unless the developer of the function did a lot more work.. a
deferred could just errback on a failure rather than having to summon
the web traceback mechanism manually.
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