"Howard Hinnant" <howard.hinnant@gmail.com> wrote in message news:D9D92951-17A4-4A29-9A0D-AD0B9E13FA64@twcny.rr.com...
On Feb 2, 2007, at 10:36 AM, Thorsten Ottosen wrote:
David Abrahams wrote:
Thorsten Ottosen <thorsten.ottosen@dezide.com> writes:
Hi,
I couldn't find a way to do this. Maybe I have overlooked something. Anyway, making sure that operator<, operator== does the right thing is pretty important.
Strict weak ordering uses a single operations and does not relate two operations. Thus you can test that < imposes a strict weak ordering, but it can have nothing to do with ==. What you're testing below would need some other name.
Right. I guess both could be useful.
One approach is to use a debugging compare predicate which adapts another predicate and adds a test. Something like:
template <class Compare> struct debug_comp { Compare comp_; debug_comp() {} explicit debug_comp(const Compare& c) : comp_(c) {}
template <class Tp, class Up> bool operator()(const Tp& x, const Up& y) { bool r = comp_(x, y); if (r) assert(!comp_(y, x)); return r; } };
Demo:
std::sort(v.begin(), v.end(), debug_comp<std::less<A> >());
SWO implies not only anti-symmetry. Did you take a look on test_strict_weak_ordering in my post? Gennadiy