Making a user-defined class std::to_string(able)

Question

I know it seems too much Java or C#. However, is it possible/good/wise to make my own class valid as an input for the function std::to_string ? Example:

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Answer 1

You could define your own to_string in its own namespace (e.g., foo).

namespace foo {
   std::string to_string(my_class const &obj) {
     return obj.string give_me_a_string_of_you();
   }
}

And use it as:

int main(){
    my_class my_object;
    std::cout<< foo::to_string(my_object);
}

Unfortunatelly, you can't define your own version of to_string in namespace std because acorrding to the standard 17.6.4.2.1 Namespace std [namespace.std] (Emphasis Mine):

The behavior of a C++ program is undefined if it adds declarations or definitions to namespace std or to a namespace within namespace std unless otherwise specified. A program may add a template specialization for any standard library template to namespace std only if the declaration depends on a user-defined type and the specialization meets the standard library requirements for the original template and is not explicitly prohibited.