[Tutor] finally without try or except

[Prasad, Ramit]

> Actually, what I'm doing is keeping a pending item log in memory as an array
> and then saving it to the DB at the end of the program, but what happens if
> the user hits ctrl-c, then the pending items array is lost. That's the use
> case that I'm looking for a solution to.

http://docs.python.org/library/exceptions.html#exceptions.KeyboardInterrupt

Ctrl-c generates a KeyboardInterrupt exception which you can catch with a
try-except clause. Of course, if the user hits ctrl-c again while 
executing the "except" portion of the python code, it will generate another
exception. The second exception will not be caught without another explicit
try-except clause and ad infinitum for the third press of ctrl-c.

You probably want to rethink your process. You can write the item log
to the db in the except clause but this can be buggy as a second ctrl-c 
will stop it. Often users will repeatedly hit ctrl-c until the program 
stops. Alternatively, you can store the item log in the db and update it 
as the program progresses. This will be the most robust as it will
also work for cases where the program is terminated without the use of 
the keyboard (i.e. kill -9, task manager, computer reboot, etc.)  but
it might also slow the program down. You could also try writing the
item log to a local file using pickle or csv.



Ramit


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