On 3/15/19 9:24 AM, Peter Levart wrote:
On 3/15/19 9:03 AM, fo...@univ-mlv.fr wrote:
* @since 13
*/
interface Once {}
What do you think of that?
It's not clear to me if an annotation, available at runtime, is not a better
fit.
Anyway, i'm not sure not sure introducing such interface/annotation worth its
maintenance cost, as you said the use case is pretty narrow.
It is narrow, but in a situation like that, where you want to code an
optimal generic algorithm and all you have access to is an Iterable,
there's no other way (short of providing additional methods, which is
ugly). Just think of this situation. You have to decide upfront if you
need to buffer the elements obtained from 1st iteration or not, but
1st iteration always succeeds...
Ok, I confess, there is a way to do it without marker interface, but is
ugly:
Iterator<T> iterator1 = iterable.iterator();
Iterator<T> iterator2;
try {
iterator2 = iterable.iterator();
} catch (IllegalStateException e) {
// we have one-shot iterable
iterator2 = null;
}
if (iterator2 == null) {
// buffer elements of iterator1 while iterating for 2nd and
subsequent iterations
...
} else {
// consume iterator1, then iterator2, then create more iterators
for subsequent iterations
...
}
Peter
