Is it possible to create a template that infers the underlying enum class type of an enum class value template parameter? I am looking to do something like the following non-working pseudo-example:
enum class MyEnumClass { e1, e2, e3 };
template<enum class T X> MyTemplate { // wrong syntax. want to specify X, infer T
using enum_class_type = T;
static constexpr enum_class_type value = X;
};
Which I would like to be instantiatable with only one parameter, e.g. MyTemplate<MyEnumClass::e1>:
static_assert( std::is_same<MyTemplate<MyEnumClass::e1>::enum_class_type, MyEnumClass>::value );
static_assert( MyTemplate<MyEnumClass::e2>::value == MyEnumClass::e2 );
I know that the following works, but it requires me to explicitly specify the enum class type as a second template parameter:
template<typename EnumClass, EnumClass X>
struct EnumValue {
using enum_class_type = EnumClass;
static constexpr enum_class_type value = X;
};
// usage: EnumValue<MyEnumClass, MyEnumClass::e1>::enum_class_type