[Python-3000] PEP 3132: Extended Iterable Unpacking (original) (raw)

Georg Brandl g.brandl at gmx.net
Thu May 3 18:12:44 CEST 2007

Steven Bethard schrieb:

On 5/3/07, Simon Percivall <percivall at gmail.com> wrote:

On 2 maj 2007, at 20.08, Guido van Rossum wrote: > [Georg] >>>>>>> a, *b, c = range(5) >>>>>>> a >>>> 0 >>>>>>> c >>>> 4 >>>>>>> b >>>> [1, 2, 3] > > > That sounds messy; only allowing *a at the end seems a bit more > manageable. But I'll hold off until I can shoot holes in your > implementation. ;-)

As the patch works right now, any iterator will be exhausted, but if the proposal is constrained to only allowing the *name at the end, wouldn't a more useful behavior be to not exhaust the iterator, making it similar to: > it = iter(range(10)) > a = next(it) > b = it or would this be too surprising? In argument lists, *args exhausts iterators, converting them to tuples. I think it would be confusing if *args in tuple unpacking didn't do the same thing. This brings up the question of why the patch produces lists, not tuples. What's the reasoning behind that?

IMO, it's likely that you would like to further process the resulting sequence, including modifying it.

Georg

-- Thus spake the Lord: Thou shalt indent with four spaces. No more, no less. Four shall be the number of spaces thou shalt indent, and the number of thy indenting shall be four. Eight shalt thou not indent, nor either indent thou two, excepting that thou then proceed to four. Tabs are right out.

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