[Python-ideas] Fwd: Why do equality tests between OrderedDict keys/values views behave not as expected?

[Guido van Rossum]

On Fri, Dec 18, 2015 at 8:07 PM, Franklin? Lee <
leewangzhong+python at gmail.com> wrote:

> If this were lists, then a lack of transitivity of elements would mean
> a lack of transitivity for lists of those elements. You get what you
> put in.
>
> But since dict views are unordered collections, a lack of transitivity
> for elements would mean INCONSISTENCY: the comparison of two views as
> multisets would depend on the exact order of comparison. Unless you
> are willing to compare everything to everything else in the worst
> case.
>

Honestly, I think it's fine if an operation like == for a collection uses
an algorithm that just assumes the items' comparison is transitive, and if
it isn't, you still get what you put it (i.e. it's still like a sewer :-).
It's the same with sort() -- if the comparison is unreasonable the sort
still terminates, just not with the items in sorted order.

-- 
--Guido van Rossum (python.org/~guido)
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