[Python-Dev] itertools predicates
tjreedy at udel.edu
Wed Nov 2 19:59:40 EDT 2016
On 11/2/2016 6:03 PM, Francisco Couzo wrote:
> Some functions that take a predicate from itertools accept None as its
>>>> list(itertools.filterfalse(None, range(10)))
>>>> list(itertools.groupby([0,0,1,1], None))
> [(0, <itertools._grouper object at 0x7fedc2047198>), (1,
> <itertools._grouper object at 0x7fedc2
> While others don't:
>>>> list(itertools.dropwhile(None, range(10)))
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> TypeError: 'NoneType' object is not callable
> I'd be interested in writing a patch to make itertools more consistent
> if there's a consensus.
> I see two possible solutions:
> * Either remove None as a predicate parameter, which would not be
> backwards compatible.
> * Or make the functions that don't accept None start accepting it.
I think you should post this as an enhancement proposal on the tracker.
Put Raymond Hettinger, the itertools originator and maintainer, as nosy.
Terry Jan Reedy
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