At Friday 15/12/2006 22:20, Leo Breebaart wrote:
I have written a function foo() that iterates over and processes
a large number of files. The function should be available to the
user as library function, via a command-line interface, and
through a GUI.
So, I added a 'config' object as a parameter to foo() that can be
used by the caller to explicitly pass in user-defined settings.
Because the processing foo() does can take such a long time, the
next thing I did was add an 'update_function' callback parameter
that foo() will call regularly, so that the GUI can update a
progress bar, and the command-line version can print dots, etc.
I now would also like to add the possibility to allow the user to
*cancel* the execution of foo() during the processing, and I am
wondering what the best / most Pythonic way to design this is.
I can't say if this is the "best/more Pythonic way", but a simple way
would be to use the return value from your callback. Consider it an
"abort" function: if it returns True, cancel execution; as long as it
returns False, keep going.
(The somewhat "reversed" meaning is useful in case the user doesn't
provide a callback at all, or it's an empty one, or it contains just
a print ".", statement, all of these returning False; so, to actually
abort the process it must have an explicit "return True" statement).
--
Gabriel Genellina
Softlab SRL
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