using enable_if with template specialization - c++

Question

I want to make function get_type_name. For types that belong to certain set example are numbers, geometry etc I want to make one get_type_name function which uses enable_if with type trait. And for each type that do not belong to particular set I want to specialize its own get_type_name function. This is my code and I get the following compiler error and can't figure out why:
error C2668: 'get_type_name': ambiguous call to overloaded function
could be 'std::string get_type_name(myenable_if::type
*)' or 'std::string get_type_name(void *)'
template<bool B, typename T = void>
struct myenable_if {};
template<typename T>
struct myenable_if<true, T> { typedef void type; };
template<class T>
struct is_number
{
static const bool value = false;
};
template<>
struct is_number<int>
{
static const bool value = true;
};
template<class T>
std::string get_type_name(void* v=0);
//get_type_name for specific type
template<>
std::string get_type_name<std::string>(void*)
{
return std::string("string");
}
//get_type_name for set of types
template<class T>
std::string get_type_name(typename myenable_if<is_number<T>::value>::type* t=0)
{
return std::string("number");
}
int main()
{
std::string n = get_type_name<int>();
}

Answer 1

Here is a working version.
#include <iostream>
#include <string>
#include <vector>
#include <iostream>
template<bool B, typename T = void>
struct myenable_if {};
template<typename T>
struct myenable_if<true, T> { typedef T type; };
template<class T>
struct is_number
{
static const bool value = false;
};
template<>
struct is_number<int>
{
static const bool value = true;
};
template<class T>
std::string get_type_name_helper(void* t, char)
{
return "normal";
}
template<class T>
typename myenable_if<is_number<T>::value, std::string>::type get_type_name_helper(void* t, int)
{
return "number";
}
//get_type_name for specific type
template<>
std::string get_type_name_helper<std::string>(void* t, char)
{
return std::string("string");
}
template <class T>
std::string get_type_name(void* t = 0)
{
return get_type_name_helper<T>(t, 0);
}
int main() {
std::string n = get_type_name<int>();
std::cout << n << '\n';
n = get_type_name<std::string>();
std::cout << n << '\n';
n = get_type_name<float>();
std::cout << n << '\n';
return 0;
}
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