PEP 322: Reverse Iteration (second revision, please comment)

[Werner Schiendl]

Alex Martelli wrote:

> 
> A built-in iterator irange -- with an optional "reverse=" argument,
> just like the very useful one you recently added to list.sort -- would be
> just as useful as revrange for the latter's use cases, AND be very handy to
> me in many more cases in which I currently use xrange and cringe each and
> every time.  Plus, specifically, I have some uses cases where:
> 
>     if mustbereversed(...):
>        seq = xrange(N-1, -1, -1)
>     else:
>        seq = xrange(N)
>     for item in seq:
>        ...
> 
> and those would get a somewhat minor benefit from either reverse OR
> revrange, since the if/else to prepare seq would still be there,
> albeit more readable along one of the two branches.  However, for this
> kind of use case, an irange with an optional reverse= would be PERFECT:
> 
>     for item in irange(N, reverse=mustbereversed(...)):
>        ...
> 
> now THAT would be blissful indeed.
> 

+1

I'd definitely prefer such a general approach to having "revrange"

However, I think it's no direct replacement for "reversed"


regards

Werner