Select function name based on template parameter - c++

Question

Is there a way to automatically select between multiple non-template functions based on a template parameter?
Example:
class Aggregate
{
public:
std::string asString();
uint32_t asInt();
private:
// some conglomerate data
};
template <typename T>
T get(Aggregate& aggregate)
{
// possible map between types and functions?
return bind(aggregate, typeConvert[T])(); ??
// or
return aggregate.APPROPRIATE_TYPE_CONVERSION();
}
The solution would be nice to throw a compiler error if there is no good conversion available, i.e.
get<double>(aggregate); // compile error
I do not want to use template specialization, i.e
template<>
int get(Aggregate& aggregate)
{
return aggregate.asInt();
}
because it leads to code duplication when your get() function has more then one line of code

Answer 1

The pedestrian way is to define each possible option separately:
template <typename T> T get(Aggregate &); // leave undefined
template <> uint32_t get(Aggregate & a) { return a.asInt(); }
// ...
Absent any more systematic structure that encodes which function serves which conversion, I think this is the best you can do. It may be worth redefining Aggregate, though, to be more introspectible.

Answer 2

You may do something like (require C++11) : (https://ideone.com/UXrQFm)
template <typename T, typename... Ts> struct get_index;
template <typename T, typename... Ts>
struct get_index<T, T, Ts...> : std::integral_constant<std::size_t, 0> {};
template <typename T, typename Tail, typename... Ts>
struct get_index<T, Tail, Ts...> :
std::integral_constant<std::size_t, 1 + get_index<T, Ts...>::value> {};
template <typename T, typename Tuple> struct get_index_in_tuple;
template <typename T, typename ... Ts>
struct get_index_in_tuple<T, std::tuple<Ts...>> : get_index<T, Ts...> {};
class Aggregate
{
public:
std::string asString();
uint32_t asInt();
private:
// some conglomerate data
};
template <typename T>
T get(Aggregate& aggregate)
{
using types = std::tuple<uint32_t, std::string>;
auto funcs = std::make_tuple(&Aggregate::asInt, &Aggregate::asString);
return (aggregate.* (std::get<get_index_in_tuple<T, types>::value>(funcs)))();
}