Stepping backwards in for loop?

[Andrew Dalke]

Steve Holden wrote:
>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'

This doesn't work they way your English description says it should;
it doesn't work on "any sequence"

>>> sreverse([1, 2, 3])
Traceback (innermost last):
  File "<interactive input>", line 1, in ?
  File "<interactive input>", line 4, in sreverse
TypeError: first argument must be sequence of strings
>>>

because while a string *acts* like a list or tuple of characters,
it really isn't.

                    Andrew
                    dalke at acm.org