[Python-ideas] Add orderedset as set(iterable, *, ordered=False) and similarly for frozenset.

[Nathaniel Smith]

On Thu, Feb 5, 2015 at 5:12 PM, Ed Kellett <edk141 at gmail.com> wrote:
> On Fri Feb 06 2015 at 12:12:19 AM Steven D'Aprano <steve at pearwood.info>
> wrote:
>>
>> I think there are plenty of other major design decisions to be made.
>> What's the union between a regular set and an ordered set? Is there a
>> frozen ordered set? Do ordered sets compare unequal if they differ only
>> in order (like lists)?
>
> Are there many options for the union question? I think the only sane choice
> for any union involving ordered sets is an unordered set - in any other case
> the resulting order would be wrong or at least not obviously right, and
> that's almost certainly better expressed explicitly.

Surely a.union(b) should produce the same result as a.update(b) except
out-of-place, and .update() already has well-defined semantics for
OrderedDicts.

-n

-- 
Nathaniel J. Smith -- http://vorpus.org