Implement create_observer.

`create_observer` takes a deferred and create a new deferred that
*observers* the original deferred. Any callbacks added to the observing
deferred will *not* affect the origin deferred.
This commit is contained in:
Erik Johnston 2015-04-27 13:59:37 +01:00
parent f46eee838a
commit 1c82fbd2eb

View File

@ -32,3 +32,22 @@ def run_on_reactor():
iteration of the main loop
"""
return sleep(0)
def create_observer(deferred):
"""Creates a deferred that observes the result or failure of the given
deferred *without* affecting the given deferred.
"""
d = defer.Deferred()
def callback(r):
d.callback(r)
return r
def errback(f):
d.errback(f)
return f
deferred.addCallbacks(callback, errback)
return d