Hello!
Just an observation.
If there were two new subtypes of Iterable introduced: IterableOnce and
IterableMultipleTimes, then all existing Iterables could be retrofitted
to implement one of these.
It wouldn't *automatically* solve the problem of 3rd party API, which
accepts an Iterable and iterates it multiple times, but would provide a
means to change that API in a straightforward way.
Also, the static analysis tools could issue a suggestion for code that
iterates Iterable more than once to switch to IterableMultipleTimes, so
that it won't be possible to pass in an IterableOnce.
It would also allow to strengthen the specification for
IterableMultipleTimes and state that all classes implementing it must
make it possible to obtain multiple iterators.
With kind regards,
Ivan
On 2/28/19 6:43 PM, Stuart Marks wrote:
Hi all,
Please review and comment on this proposal to allow Stream instances
to be used in enhanced-for ("for-each") loops.
Abstract
Occasionally it's useful to iterate a Stream using a conventional
loop. However, the Stream interface doesn't implement Iterable, and
therefore streams cannot be used with the enhanced-for statement. This
is a proposal to remedy that situation by introducing a new interface
IterableOnce that is a subtype of Iterable, and then retrofitting the
Stream interface to implement it. Other JDK classes will also be
retrofitted to implement IterableOnce.
Full Proposal:
http://cr.openjdk.java.net/~smarks/reviews/8148917/IterableOnce0.html
Bug report:
https://bugs.openjdk.java.net/browse/JDK-8148917
Webrev:
http://cr.openjdk.java.net/~smarks/reviews/8148917/webrev.0/
Note, this changeset isn't ready to push yet. In particular, it has no
tests yet. However, the implementation is so simple that I figured I
should include it. Comments on the specification wording are also
welcome.
Thanks,
s'marks
--
With kind regards,
Ivan Gerasimov
