Is specialization of std::to_string for custom types allowed by the C++ standard?

Question

In C++11 and later, is it allowed to specialize std::to_string in the std namespace for custom types?

namespace std {
string to_str         


        

Answer 1

If I'm not mistaken you can simply overload to_string for a generic type:

template to_string(const T& _x) {
    return _x.toString();
}

and this allows use of ADL (argument dependent lookup) by your program to correctly choose the relevant to_string method based upon the type passed.