printable.cc

#include <iostream>
#include <string>
#include <type_traits>
#include <utility>
using namespace std;

void print(const string& str) {
    cout << str << endl;
}

template<typename T>
struct printable {
    template<typename C>
    static char test(typename add_pointer<decltype(print(declval<C>()))>::type);

    template<typename C>
    static double test(...);

    enum { value = sizeof(test<T>(nullptr)) == 1 };
};

template<typename T>
bool check_if_printable() {
    return printable<T>::value;
}

int main(void)
{
    cout << "string " << check_if_printable<string>() << endl;
    cout << "const char* " << check_if_printable<const char*>() << endl;
    cout << "char[2] " << check_if_printable<char[2]>() << endl;
    cout << "int " << check_if_printable<int>() << endl;
    cout << "double " << check_if_printable<double>() << endl;
    cout << "const string& " << check_if_printable<const string&>() << endl;
    cout << "string& " << check_if_printable<string&>() << endl;
    cout << "string&& " << check_if_printable<string&&>() << endl;
    cout << "const char*& " << check_if_printable<const char*&>() << endl;
    cout << "char*& " << check_if_printable<char*&>() << endl;
}