Part of twisted.internet.defer.Deferred View Source
Deferred
.
Each callback will have its result passed as the first argument to the
next; this way, the callbacks act as a 'processing chain'. If the
success-callback returns a Failure
or
raises an Exception
,
processing will continue on the *error* callback chain. If a callback (or
errback) returns another Deferred
, this
Deferred
will be chained to it (and further callbacks will not run until that Deferred
has a
result).
An instance of Deferred
may
only have either callback
or errback
called on it, and only once.
Parameters | result | The object which will be passed to the first callback added to this Deferred (via
addCallback ). |
Raises | AlreadyCalledError | If callback
or errback
has already been called on this Deferred . |