[Python-Dev] Re: PEP 322: Reverse Iteration (original) (raw)

Phillip J. Eby pje at telecommunity.com
Wed Nov 5 12:02:09 EST 2003

At 07:28 AM 11/5/03 -0800, Guido van Rossum wrote:

> Why not change enumerate() to return an iterable, rather than an > iterator? Then its reversed method could attempt to delegate to > the underlying iterable. Is it likely that anyone relies on > enumerate() being an iterator, rather than an iterable?

I find it rather elegant to use enumerate() on a file to generate line numbers and lines together (adding 1 to the index to produce a more conventional line number). What's more elegant than for i, line in enumerate(f): print i+1, line, to print a file with line numbers??? I've used this in throwaway code at least, and would hate to lose it.

I thought 'for x in y' always called 'iter(y)', in which case the above still works. It's only this:

ef = enumerate(f)

while 1: try: i,line = ef.next() print i+1, line, except StopIteration: break

That would break.

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