[Twisted-Python] deferred proposed update

[James Y Knight]

On Jan 29, 2004, at 10:09 AM, Glyph Lefkowitz wrote:

> Fabrice Coudert wrote:
>
>> So, I restate the probleme with chainDeferred :
>> chainDeferred(d) is equivalent to addCallbacks(d.callback, d.errback),
>> but this two methods are not really sort of callback methods for
>> deferred coz they didn't return a result.
>
> This is not a problem, this is a specification of the way it works.  
> chainDeferred is a holdover from before one could sensibly return one 
> Deferred from the callback to another.  If you want to add callbacks 
> in some other way, don't use chainDeferred.

So, the right way to do what he asks is...? Perhaps this?

my_defer = getADeferredForSomething()
new_defer = defer.Deferred()
new_defer.addCallback(preprocessing)
new_defer.addCallback(lambda x: return my_defer)
new_defer.addCallback(postprocessing)
my_defer = new_defer

James