Stepping backwards in for loop?

[Steve Holden]

"Andrew Dalke" <dalke at acm.org> wrote in message
news:9banud$ge$1 at slb6.atl.mindspring.net...
> Carlos Ribeiro wrote:
> >It would be a *lot* easier if strings had a reverse method, or if the
> >reverse() methods returned the reversed string. However, similarly to
> >sort(), the Python-way-of-doing-things must have some good reason for
> >reverse() to behave this way (as a inplace operation on the list).
>
> Lists have a reverse method because lists are mutable.
> Consider strings as more akin to tuples.  Both are immutable.
>
But there's no good reason why there shouldn't be a "reverse" function which
returns the reverse of any sequence, surely? The question then becomes
whether a built-in function could improve on the efficiency of

>>> def sreverse(s):
...  l = list(s)
...  l.reverse()
...  return "".join(l)
...
>>> sreverse("abcdefg")
'gfedcba'

I'd be very surprised if it couldn't ... though then there's Unicode to take
into account.

regards
 STeve