[Python-ideas] Where did we go wrong with negative stride?

[Barry Warsaw]

On Oct 28, 2013, at 11:00 PM, Nick Coghlan wrote:

>In this vein, I started wondering if it might be worth trying to come up
>with a syntax to control whether the ends of a slice were open or closed.
>
>Since mismatched paren types would be too confusing, perhaps abusing some
>binary operators as Chris suggested could help:
>
>"[<i:" closed start of slice (default)
>"[i<:" open start of slice
>":>j]" open end of slice (default)
>":j>]" closed end of slice
>":>j:k]" open end of slice with step
>":j>:k]" closed end of slice with step
>
>Default slice: "[<0:-1>:1]"
>Reversed slice: "[<-1:0>:-1]"
>
>This makes it possible to cleanly include the final element as a closed
>range, rather than needing to add or subtract 1 (and avoids the zero trap
>when indexing from the end).

Sorry, I'm -1 here.  I think it's already difficult enough to teach, read, and
comprehend what's going on with slice notation when there are strides
(especially negative ones).  I don't think this syntax will make it easier to
understand at a glance (or even upon some deeper inspection).

-Barry
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 836 bytes
Desc: not available
URL: <http://mail.python.org/pipermail/python-ideas/attachments/20131028/5d91d65e/attachment.sig>