Patrick Maupin wrote: >>After considering several alternatives and trying out a few ideas with a >> modified list object Bengt Richter posted, (Thank You), I think I've >>found a way to make slice operation (especially far end indexing) >>symmetrical and more consistent. > > > I don't know that it makes it more consistent. I could be persuaded, > but it would have to be by real-life examples with calculated slice > indices and stride. I do this thing all the time, and find the current > rules simple and very consistent. Occasionally, I might wish that > things were a little different, but there is always a workaround. I > would have to see some real code examples, of sufficient scope to see > that there are fewer workarounds with this proposal than with the > current implementation.
I'll post a few examples once I'm sure the list object works correctly and then you can play around with it and try it out as well. > FWIW, there is a reasonable workaround for the case where the indices > might be negative and you would like zero or greater to mean 'end of > list'. If "x" is the index variable, you can use the expression (x<0 > and x or None) for the index value in the slice. If you find yourself > doing this often, you can write a little function for it -- def > EndIndex(x): return x<0 and x or None. Thanks, this is a good example. Yes it does remove the need for a work around in those cases. You still need to check for cases where you may cross the -1,0 boundary while incrementing or decrementing an index. But that is an expected condition and easily handled with an 'if' or 'for' loop. > But in real code, I fear you might need a similar helper function for > similar issues with your change. I just don't know what those are > without more thought. > > Regards, > Pat Thanks for the feedback, it was helpful. Cheers, Ron -- http://mail.python.org/mailman/listinfo/python-list
