RFR(s): 8072726: add adapter to convert Enumeration to Iterator

[Stuart Marks]

Hi guys, really going at it on a Saturday, eh?

On 5/16/15 3:46 PM, Claes Redestad wrote:
> I also realized Iterable should typically allow multiple passes over the
> collection/enumeration, so this wouldn't feel right. Sorry!
>
> So... I'm happy with Stuart's proposal.

Yep, that's the main reason not to have Enumeration extend Iterable. Although it 
isn't written down explicitly, common usage expects that each call to iterator() 
produce a fresh instance, positioned at the beginning, independent of other 
instances.

> I would also be happy (happier?) with a stream variant:
> pc.elements().stream().forEach(this::doSomethingWithPermission);

I think Rémi answered this well.

>> and remember, prefer composition to inheritance :)
>
> *ducks* :)

Yep. While we're at it, though, the "obvious" alternative is to have Enumeration 
extend Iterator (as opposed to Iterable). This could work, but it has a fairly 
big risk of incompatibility. Iterator<T> defines a next() method returning T, 
and it seems pretty likely that there's code out there that has a next() method. 
If it returned T, it wouldn't be an error, but the resulting Iterator probably 
wouldn't function properly. If it returned something other than T, it'd be a big 
source incompatibility.

Of course, in principle, the same thing could occur with "asIterator". But that 
seems much less likely to collide with something than "next".

s'marks

>
> /Claes
>
>>
>>>
>>> /Claes
>>
>> Rémi
>>
>>>
>>> On 2015-05-16 02:37, Stuart Marks wrote:
>>>> Hi all,
>>>>
>>>> Please review this small API enhancement to add a default method
>>>> "asIterator()" to Enumeration that converts it into an Iterator.
>>>>
>>>> Webrev:
>>>>
>>>> http://cr.openjdk.java.net/~smarks/reviews/8072726/webrev.0/
>>>>
>>>> Bug:
>>>>
>>>>     https://bugs.openjdk.java.net/browse/JDK-8072726
>>>>
>>>> Thanks,
>>>>
>>>> s'marks
>>>
>>
>