EnumSet doesn't implement SequencedSet

[Aaron Scott-Boddendijk]

> It doesn't seem like the members of an EnumSet would be iterated
frequently...

We use EnumSet and EnumMap extensively, frequently iterating over them (the
enum's natural order being critical).

> ...usually treated as a bag of named booleans used as a set of boolean
options.

So for us it's... "ordered bag of named booleans with cheap lookup".

But I agree our usage probably wouldn't benefit from sequenced/navigable
functionality much (if at all).

--
Aaron Scott-Boddendijk

On Wed, May 24, 2023 at 5:51 AM Stuart Marks <stuart.marks at oracle.com>
wrote:

> The idea of EnumSet implementing SortedSet or NavigableSet has been around
> for a long time; see
>
>     https://bugs.openjdk.org/browse/JDK-6278287
>
> But yes, EnumSet could also implement SequencedSet. Similarly, EnumMap
> could implement SequencedMap, SortedMap, or NavigableMap.
>
> Implementing NavigableSet/Map is somewhat onerous, given that there's no
> AbstractNavigableSet/Map, and there are a lot of methods and variations of
> views to be implemented.
>
> I'm a bit skeptical about the usefulness of retrofitting EnumSet/Map this
> way, though. My hunch is that EnumSet is usually treated as a bag of named
> booleans used as a set of boolean options. The EnumSet is passed around as
> an aggregate, with individual enum instances tested at specific points in
> the code to adjust the logic. It doesn't seem like the members of an
> EnumSet would be iterated frequently, or that it would be useful to have
> specific subsets of an EnumSet (which is what NavigableSet would provide).
> Maybe similar analysis applies to EnumMap.
>
> I could be convinced otherwise with use cases, though.
>
> s'marks
>
>
> On 5/23/23 2:57 AM, Tagir Valeev wrote:
>
> Hello!
>
> Looks like this was overlooked. On the other hand, it could even implement
> SortedSet or Navigable set, as it's essentially not just ordered but
> sorted, according to the enum natural order. Same for EnumMap.
>
> With best regards,
> Tagir Valeev
>
> On Tue, May 23, 2023, 11:46 Andrey Turbanov <turbanoff at gmail.com> wrote:
>
>> Hello.
>> I've noticed that EnumSet unfortunately doesn't implement the newly
>> introduced interface SequencedSet.
>> From the first look it fits into it.
>> Is there a reason for that? Sorry if it was already discussed.
>>
>> Andrey Turbanov
>>
>
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