Map enum value to a type in C++

Question

Is there any way to map enum values to types in C++, including C++11.
I have the following enum type:

enum ATTRIBUTE{AGE=0, MENOPAUSE, TUMOR_SIZE, INV_NODES, NODE_CAPS,
               DEG_MALIG, BREAST, BREAST_QUAD, IRRADIAT, CLASS};

I want to map each value of this enum to a certain type. I want to map AGE to int, MENOPAUSE to another enum type, BREAST to bool and so on.
So is it possible to create a function which returns a value of type which depends on the value of the attr variable?

//Like that:
auto value = map_attr(ATTRIBUTE attr);
//Here the type of the value variable should be int if the attr variable is AGE, bool for BREAST and so on.

Answer 1

An idiomatic way to do it is using traits:

enum ATTRIBUTE{ AGE=0, MENOPAUSE, TUMOR_SIZE, INV_NODES, NODE_CAPS, DEG_MALIG, BREAST, BREAST_QUAD, IRRADIAT, CLASS };

template<ATTRIBUTE> struct Map;

template<> struct Map<AGE> {
    using type = int;
    static constexpr type value = 42;
};

template<> struct Map<MENOPAUSE> {
    using type = AnotherEnumType;
    static constexpr type value = AnotherEnumType::AnotherEnumValue;
};

// ...

Then you can define map_attr as a function template:

template<ATTRIBUTE A>
typename Map<A>::type map_attr() { return Map<A>::value; }

And use it as:

auto something = map_attr<AGE>();

---

It follows a minimal, working example:

#include<type_traits>

enum ATTRIBUTE{ AGE=0, MENOPAUSE };

template<ATTRIBUTE> struct Map;

template<> struct Map<AGE> {
    using type = int;
    static constexpr type value = 42;
};

template<> struct Map<MENOPAUSE> {
    using type = double;
    static constexpr type value = 0.;
};

template<ATTRIBUTE A>
typename Map<A>::type map_attr() { return Map<A>::value; }

int main() {
    static_assert(std::is_same<decltype(map_attr<AGE>()), int>::value, "!");
    static_assert(std::is_same<decltype(map_attr<MENOPAUSE>()), double>::value, "!");
}