On Wed, Mar 30, 2011 at 4:50 PM, Jasper St. Pierre <jstpierre@mecheye.net> wrote:
The problem that I have is that errback flow is awkward... the main difference is that addCallbacks will call the errback if its own callback fails, right? I can only see that really being useful by accident.
Not really. # 1. Handle error then do the action anyway. deferred = order_food() deferred.addErrback(handle_error) deferred.addCallback(do_action) # 2. Handle the error but do the action only if # the error doesn't occur. deferred = order_food() deferred.addCallbacks(do_action, handle_error) # 3. Handle the error for the entire operation. deferred = order_food() deferred.addCallback(do_action) deferred.addErrback(handle_error) # 4. Do something regardless of success or failure. deferred = order_food() deferred.addBoth(do_cleanup) These are analogous to: # 1. Handle error then do the action anyway. try: value = order_food() except: handle_error() do_action(value) # 2. Handle the error but do the action only if the error doesn't occur. try: value = order_food() except: handle_error() else: do_action(value) # 3. Handle the error for the entire operation. try: value = order_food() do_action(value) except: handle_error() # 4. Do something regardless of success or failure. try: value = order_food() finally: do_cleanup()
jml PS. Please don't top post to this list.