[Twisted-Python] understanding deferreds
exarkun at twistedmatrix.com
exarkun at twistedmatrix.com
Thu Jan 28 15:39:03 MST 2010
On 10:28 pm, msoulier at digitaltorque.ca wrote:
>Hello,
>
>I've been reading up on this
>
>http://twistedmatrix.com/documents/current/core/howto/defer.html
>
>I'm a bit confused as to the "visual explanation". It seems like if you
>have a
>single callback and errback, that if the errback wants to swallow the
>error,
>the callback will not be called at all, since deferred processing will
>look
>for the second callback at that point by the diagram.
There are at least three ways you can have a single callback and
errback:
d.addCallback(cb)
d.addErrback(eb)
or
d.addErrback(eb)
d.addCallback(cb)
or
d.addCallbacks(cb, eb)
All three of these do something different.
>So, right now I'm calling my own callback from the errback if I want to
>swallow the error. Is there a better way?
It sounds like you want the middle option above.
Jean-Paul
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