[Python-ideas] Consider making enumerate a sequence if its argument is a sequence

[Chris Barker]

On Thu, Oct 1, 2015 at 12:37 PM, Steven D'Aprano <steve at pearwood.info>
wrote:

> This makes a difference. Just a few days ago, somebody mis-reported a
> supposed "bug" in all() and any(). For example:
>
> values = (x%5 == 3 for x in range(8))
> print(list(values))
> print(all(values))  # should return False
>
> Obvious error is obvious: having printed out the values from the
> generator expression, values is now exhausted, and all() of the empty
> set is True (vacuous truth). The difference between general iterables
> which may or may not be one-shot iterators, and those which are
> definitely not iterators, is not always just an implementation detail.


they used a generator expression, when they clearly wanted a list
comprehension -- so yes, it matters what they were getting, I don't know
that adding more vocabulary would help prevent people from making that
mistake...

if they had been smart enough to call the list() again, before claiming
there was a bug in all -- it may have explained itself.

-Chris







>
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> Steve
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