[Python-ideas] Propagating StopIteration value
storchaka at gmail.com
Sun Oct 7 21:30:16 CEST 2012
On 07.10.12 04:45, Guido van Rossum wrote:
> But yes, this was all considered and accepted when PEP 380 was debated
> (endlessly :-), and I see no reason to change anything about this.
The reason is that when someone uses StopIteration.value for some
purposes, he will lose this value if the iterator will be wrapped into
itertools.chain (quite often used technique) or into other standard
> "Don't do that" is the best I can say about it -- there are a zillion
> other situations in Python where that's the only sensible motto.
The problem is that two different authors can use two legal techniques
(using values returned by "yield from" and wrap iterators with
itertools.chain) which do not work in combination. The conflict easily
solved if instead of standard itertools.chain to use handwriten code. It
looks as bug in itertools.chain.
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