If I'm not mistaken, this is basically template metaprogramming, and you're going to get your answers at compile-time (which means your inputs are also locked-i

If I'm not mistaken, this is basically template metaprogramming, and you're going to get your answers at compile-time (which means your inputs are also locked-in at compile-time). For applications that, for example, get the countries and/or colors from a user or database at runtime, wouldn't it be better to use a constraint solver library instead?