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> >()); It isn't an exhaustive test, but does tend to catch such bugs in the wild. A disadvantage of this approach is that it may upset some algorithms which only require comp(x,y) but not comp(y,x) to be valid.