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

Claes Redestad claes.redestad at oracle.com
Sat May 16 22:46:39 UTC 2015

On 2015-05-16 23:48, Remi Forax wrote:

On 05/16/2015 06:21 PM, Claes Redestad wrote: Hi,

any reason not to just have Enumeration extend Iterable and default-implement iterator()? http://cr.openjdk.java.net/~redestad/scratch/enumerable.00/ I guess there are compatibility risks I haven't thought through completely, but I think concrete classes that already implement both Enumeration and Iterable should continue to work as expected (since the concrete class' implementation of iterator always takes precedence), no? Hi Claes, yes, but there is an issue for code that uses instanceof to do something different if the object is an Enumeration or if the object is an Iterable.

Hi Rémi,

I guess that's a possibility.

You can only retrofit an existing class/interface to implements/extends an interface/class in a compatible way only if the interface/class is newly introduced in the release by example retrofitting Closeable to implement AutoCloseable is Ok in 1.7 because AutoCloseable was introduced in 1.7.

Probably due to introducing ambiguity in overload selection, come to think of it.

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.

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

and remember, prefer composition to inheritance :)

ducks :)

/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

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