I have used constrained_value to prototype a fixed-pt class. It seems to be developing nicely. One thing might be useful is to have the option to record minimum and maximum values that are used during a given computation. Right now, I have: template<int int_bits, int frac_bits, typename base_type=int, typename error_policy=cv::throw_exception<>, typename round_policy=rnd<frac_bits,base_type> > struct fixed_pt : ... { typedef fixed_pt<int_bits,frac_bits,base_type,error_policy,round_policy> self; static const int total_bits = int_bits + frac_bits; static const base_type max = ~(base_type(-1) << (total_bits-1)); static const base_type min = (base_type(-1) << (total_bits-1)); typedef typename cv::bounded_int<base_type, min, max,true,true,error_policy>::type val_t; ... val_t value; } So fixed_pt<> contains a bounded_int member. I'm wondering how to add a facility to track extremal values. It would seem to be nice to add it into the 'value' member itself, but I suspect this concept doesn't really fit with the constrained_value design.