[Twisted-Python] understanding deferreds

Tristan Seligmann mithrandi at mithrandi.net
Thu Jan 28 17:56:55 EST 2010

On Fri, Jan 29, 2010 at 12:39 AM,  <exarkun at twistedmatrix.com> wrote:
> 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)

Just to expand on exarkun's answer a little, it might help to
understand that addCallback and addErrback are simply implemented in
terms of addCallbacks. Roughly:

def passthru(arg):
    return arg

d.addCallback(cb) is equivalent to d.addCallbacks(cb, passthru)

d.addErrback(eb) is equivalent to d.addCallbacks(passthru, eb)
mithrandi, i Ainil en-Balandor, a faer Ambar

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