The following code example is taken from the book
C++ Templates - The Complete Guide, 2nd Edition
by David Vandevoorde, Nicolai M. Josuttis, and Douglas Gregor,
Addison-Wesley, 2017
© Copyright David Vandevoorde, Nicolai M. Josuttis, Douglas Gregor 2017
template<bool val>
struct BoolConstant {
using Type = BoolConstant<val>;
static constexpr bool value = val;
};
using TrueType = BoolConstant<true>;
using FalseType = BoolConstant<false>;