On 2020-12-26 18:03, Chris Angelico wrote:
On Sun, Dec 27, 2020 at 11:36 AM Greg Ewing <greg.ew...@canterbury.ac.nz> wrote:
On 27/12/20 10:15 am, Christopher Barker wrote:
> It does seem like ** could be usable with any iterable that returns
> pairs of objects. However the trick is that when you iterate a dict, you
> get the keys, not the items, which makes me think that the only thing
> you should *need* is an items() method that returns an iterable (pf
> pairs of objects).
It seems to me it would be more fundamental to use iteration to get
the keys and indexing to get the corresponding values. You're only
relying on dunder methods then.
But that would mean that a lot of iterables would look like mappings
when they're not. Consider:
def naive_items(x):
... return [(key, x[key]) for key in x]
...
naive_items(range(9, -1, -1))
[(9, 0), (8, 1), (7, 2), (6, 3), (5, 4), (4, 5), (3, 6), (2, 7), (1, 8), (0, 9)]
I don't see that as a major problem. It is no more "surprising" than
doing something like list('abc') and getting ['a', 'b', 'c']. If you do
{**range(9, -1, -1)} you may get a result that looks strange or isn't
useful, but as long as the result is consistent with the protocol,
that's fine. Just don't use **-unpacking with ranges if you don't want to.
--
Brendan Barnwell
"Do not follow where the path may lead. Go, instead, where there is no
path, and leave a trail."
--author unknown
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