Andrew Sutton skrev:
My point was that a default constructed range may be in a perfectly valid
state, too, depending on its iterators.
Indeed. I think that a default constructed iterator_range should be usable and empty iff default constructed iterators are non-singular and equal. This effectively pushes dealing with default construction onto the iterators. IMO, this is more consistent than the old behavior, where a default constructed iterator_range was "empty", but r.begin() == r.end() could be undefined behavior.
I think this is the right answer (and pretty well argued by now). The behavior of the iterator_range should "inherit" (is there a better word for this?) its semantics from the underlying iterator. To do otherwise would impose requirements on iterators that may not (easily) support those semantics, making the concept less generic (as in represents fewer possible implementations).
Well, it is fairly easy to remove some of the debug-checks from the code. Do I understand you correctly in that you want them all removed? -Thorsten