Hi Andrew again, 2012/5/8 Joachim Faulhaber <afojgo@googlemail.com>:
2012/5/7 Andrew Hundt <athundt@gmail.com>:
IMO it would seem reasonable and useful to 'support' NaN.
I don't think the ICL should support NaN. Moreover I believe boost libraries and generic concepts should not integrate NaN in general. In a way I conceive NaN as being "anti generic". Wherever I run into the NaN phenomenon, it tends to jeopardize simplicity and elegance in generic designs.
NaNtheLess! I found a generic solution to the problem :) Look how flexible generic designs can be :) Even in the presence of an awkward and self-contradicting idea like NaN, the desired behavior seems to be implementable with the tools provided by the generic design. We can complete the ordering relation in a way such that NaN is smaller than all regular values, by defining the comparison functor 'NaNTheLess': template<class Float> struct NaNtheLess { bool operator()(Float lhs, Float rhs)const { return tr1::isnan(lhs) ? !tr1::isnan(rhs) : std::less<Float>()(lhs, rhs); } }; BOOST_AUTO_TEST_CASE(NaNtheLessTest) { typedef interval_set<double, NaNtheLess> NaNy_SetT; typedef NaNy_SetT::interval_type NaNy_IntervalT; NaNy_SetT nanySet; double NaN = numeric_limits<double>::quiet_NaN(); nanySet.insert(NaN); nanySet.insert(42); cout << nanySet << endl; nanySet.insert(NaNy_IntervalT::right_open(40,42)); BOOST_CHECK(contains(nanySet, NaN)); BOOST_CHECK(contains(nanySet, 42)); nanySet.insert(NaNy_IntervalT::right_open(40,42)); cout << nanySet << endl; nanySet += NaNy_IntervalT::right_open(NaN,42); cout << nanySet << endl; double Min = (numeric_limits<double>::min)(); nanySet -= Min; cout << nanySet << endl; nanySet += Min; cout << nanySet << endl; } //---- Output --------------------------- {[1.#QNAN,1.#QNAN][42,42]} {[1.#QNAN,1.#QNAN][40,42]} {[1.#QNAN,42]} {[1.#QNAN,2.22507e-308)(2.22507e-308,42]} {[1.#QNAN,42]} Hope this solves your problems. NaNtheless, I am a NaN loather ;) Cheers, Joachim -- Interval Container Library [Boost.Icl] http://www.joachim-faulhaber.de