While looking for a generic way to perform an enum cast, I stumbled across an interesting solution posted here. In order to strengthen the underlying enum data types, I tried to replace the conventional enum with a C++11 enum class as follows:
// generic code
#include <algorithm>
template <typename T>
struct enum_traits {};
template<typename T, size_t N>
T *endof(T(&ra)[N]) {
return ra + N;
}
template<typename T, typename ValType>
T check(ValType v) {
typedef enum_traits<T> traits;
const T *first = traits::enumerators;
const T *last = endof(traits::enumerators);
if (traits::sorted) { // probably premature optimization
if (std::binary_search(first, last, v)) return T(v);
}
else if (std::find(first, last, v) != last) {
return T(v);
}
throw "exception";
}
/*
// "enhanced" definition of enum
enum e {
x = 1,
y = 4,
z = 10,
};
*/
// new C++11 enum class
enum class e : int {
x = 1,
y = 4,
z = 10,
};
template<>
struct enum_traits<e> {
static const e enumerators[];
static const bool sorted = true;
};
// must appear in only one TU,
// so if the above is in a header then it will need the array size
const e enum_traits<e>::enumerators[] = { e::x, e::y, e::z };
// usage
int main() {
e good = check<e>(1);
e bad = check<e>(2);
}
However, this leads to a crash during the compilation process (error C1001: An internal error has occurred in the compiler.). I can't seem to figure out what's causing this, but my guess is that the std::find() and/or std::binary_search() functions are having problems dealing with the enum class. Has someone experienced a similar issue yet?
