[Twisted-Python] Re: DeferredList.addDeferred behaviour

Andrew Bennetts andrew-twisted at puzzling.org
Thu Feb 26 21:31:47 EST 2004

On Thu, Feb 26, 2004 at 10:48:12AM -0500, David Bolen wrote:
> Without addDeferred I need to aggregate the underlying deferreds
> separately, but more importantly, I need a completely separate loop to
> install the suppression errbacks, because that has to be done _after_
> the Deferreds are stuck into the DeferredList or else that suppression
> will stop the DeferredList from seeing the error.

Interesting.  I think I'd still rather the two loops than the confusing
semantics of addDeferred.

> Although if DeferredList were to grow a way to specify that it should
> suppress errors once it has gathered them, I'd probably be just as
> happy as having addDeferred fixed, since the separate loop for error
> suppression bugs me more than the need to separately aggregate the
> Deferreds together before creating the DeferredList.  Actually
> suppressing errors might make me even happier, since needing to
> suppress the errors separately (noted in the API documentation, but
> not the HowTo), while making perfect sense to me now, took a while to
> catch on to initially.

I think adding a 'consumeErrors' or 'suppressErrors' flag might be a good
idea... I've put a patch up at http://twistedmatrix.com/bugs/issue528 --
let's continue discussion there.

In the meantime, I've checked in the change to deprecate addDeferred, and
removed it from the howto.


More information about the Twisted-Python mailing list