Iterable.stream()

[Kevin Bourrillion]

On Thu, Feb 21, 2013 at 8:14 AM, Joe Bowbeer <joe.bowbeer at gmail.com> wrote:

> Is this something we should address?  There was no discussion about this
> last time.
>
I still think it is. It's true that anyone who inherits the *default *stream()
will get one that's only as good as their (possibly lousy) iterator always
is, but that's the best we can do.



> On Feb 21, 2013 8:07 AM, "Kevin Bourrillion" <kevinb at google.com> wrote:
>
>> 1. Yes please.
>> 2. And this time I won't hijack the thread.
>>
>>
>> On Thu, Feb 21, 2013 at 7:44 AM, Brian Goetz <brian.goetz at oracle.com>wrote:
>>
>>> Currently we define stream() and parallelStream() on Collection, with
>>> defaults like:
>>>
>>>     default Stream<E> stream() {
>>>         return Streams.stream(
>>>            () -> Streams.spliterator(iterator()**, size(),
>>>                                      Spliterator.SIZED),
>>>            Spliterator.SIZED);
>>>     }
>>>
>>> In other words, if a Collection does not override stream(), it gets the
>>> stream based on the iterator.
>>>
>>> It has been suggested that we could move stream/parallelStream() up to
>>> Iterable.  They could use an almost identical default, except that they
>>> don't know the SIZED flag.  (The default in Collection would stay, so
>>> existing inheritors of the Collection default wouldn't see any difference.
>>>  (This is why default methods are virtual.))
>>>
>>> Several people have asked why not move these to Iterable, since some
>>> APIs return "Iterable" as a least-common-denominator aggregate type, and
>>> this would allow those APIs to participate in the stream fun.  There are
>>> also a handful of other types that implement Iterable, such as Path
>>> (Iterable<Path>) and DirectoryStream (where we'd added an entries() method,
>>> but that would just then become stream()).
>>>
>>> The sole downside is that it creates (yet another) external dependency
>>> from java.lang.Iterable -- now to java.util.stream.
>>>
>>> Thoughts?
>>>
>>>
>>
>>
>> --
>> Kevin Bourrillion | Java Librarian | Google, Inc. | kevinb at google.com
>>
>


-- 
Kevin Bourrillion | Java Librarian | Google, Inc. | kevinb at google.com
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