Nevin Liber wrote:
On 8 January 2013 12:09, Peter Dimov <lists@pdimov.com> wrote:
Yes, I agree. To expand on that, the requirements defined by the standard library such as CopyConstructible, LessThanComparable, and so on, do not have preconditions. So if a movable type claims to conform to these requirements, it can't impose a precondition that the operations only work on values that haven't been moved from.
I believe it can. Take n3485 25.4p3 (Sorted and related operations): "For algorithms other than those described in 25.4.3 to work correctly, comp has to induce a strict weak ordering on the values."
This, for instance, allows sorting of doubles as long as none of them are NaN.
If I have the values { 1, 7, 5, -3 } and a predicate that works correctly for these specific values, but returns garbage for others, does it satisfy the requirement? An interesting question... for another time, maybe.