Mapping an integral template parameter value onto a primitive type

Question

I want to map a number to a type. For this example I\'ll make a function that maps a sizeof() result onto a signed primitive type.

I am wondering if there is a bette

Answer 1

I would not use C++17 if constexpr for this, instead I'd use template specialization, as it looks more declarative to me.

Something along the following lines:

template struct SizeToType {static_assert(S != S, "Wrong size"); };

template<> struct SizeToType<1> { using type = uint8_t; };
template<> struct SizeToType<2> { using type = uint16_t; };
template<> struct SizeToType<4> { using type = uint32_t; };
template<> struct SizeToType<8> { using type = uint64_t; };

template
using SizeToToTypeT = typename SizeToType::type;

Adding more types would be just adding more specializations (one-liners) here.