----- Mail original -----
> De: "Peter Levart" <peter.lev...@gmail.com>
> À: "Remi Forax" <fo...@univ-mlv.fr>, "Brian Goetz" <brian.go...@oracle.com>
> Cc: "core-libs-dev" <core-libs-dev@openjdk.java.net>
> Envoyé: Jeudi 21 Mars 2019 15:54:21
> Objet: Re: Proposal: JDK-8148917 Enhanced-For Statement Should Allow Streams
> On 3/21/19 2:17 PM, fo...@univ-mlv.fr wrote:
>> for some reason i was convinced that IntStream.iterator() was returning a
>> PrimitiveIterator.OfInt and not an Iterator<Integer>,
>> so yes, it will work but i don't understand why it's not BaseStream instead
>> of
>> Stream<Object> that inherits from Iterable.
>
> I think it's the Iterable.forEach(Consumer<? super T>) that would clash
> with IntStream.forEach(IntConsumer), LongStream.forEach(LongConsumer)
> and DoubleStream.forEach(DoubleConsumer) if Iterable was a supertype of
> BaseStream.
>
> ...unless IntConsumer was made to extend Consumer<Integer>, LongConsumer
> was made to extend Consumer<Long> and DoubleConsumer was made to extend
> Consumer<Double>...
>
> I tried that and it (almost) compiles. The sole problem presents the
> following class:
>
> public class LongSummaryStatistics implements LongConsumer,
> IntConsumer { ...
>
> So I had another idea. What if IntConsumer, LongConsumer and
> DoubleConsumer were all made to extend Consumer<Number> ?
>
> In that case LongSummaryStatistics would only have to override the
> method to disambiguate it.
>
> By doing that, the problem springs in java.util.stream.Sink hierarchy
> (Sink<T> extends Consumer<T>) where Sink.OfInt extends both
> Sink<Integer> and IntConsumer...
>
> Perhaps this could be fixed (as it is internal non-public API), but the
> same problem could exist in 3rd party code...
having a class that implements 2 consumers like IntConsumer and LongConsumer is
hard to retrofit if as you said IntConsumer is a subtype of Consumer<Int> and
LongConsumer is a subtype of Consumer<Long>, it means that the bridge
accept(Object) has to dispatch to accept(int) and accept(long) at the same time
A code like
Object o = ...
Consumer c = new LongSummaryStatistics(...);
c.accept(o);
shows the issue.
Having LongSummaryStatistics implementing IntConsumer was a mistake in
retrospect.
so thanks, i've my answer why BaseStream can not implement Iterable until at
least we have reified generics.
>
> Regards, Peter
regards,
Rémi
