Sample std::enable-if in c++

enable-if.cc

#include <iostream>
#include <string>
#include <type_traits>

// Custom data structures.
struct Car{
    std::string name;
};
struct Bike{
    std::string name;
};
struct Walk{
    std::string name;
};

// Custom traits.
template <typename T>
struct IsVehicle {
  static const bool value = false;
};

template <>
struct IsVehicle<Car> {
  static const bool value = true;
};

template <>
struct IsVehicle<Bike> {
  static const bool value = true;
};

// Enable function if T is Car or Bike.
template <class T>
typename std::enable_if<IsVehicle<T>::value>::type Repair(T data_type) {
    std::cout << "Repairing has started..." << data_type.name << std::endl;
}

int main() {
    auto data_car = Car{name:"c1"};
    Repair(data_car);

    auto data_bike = Bike{name:"b1"};
    Repair(data_bike);

    // ERR
    //auto data_walk = Walk{name:"w1"};
    //Repair(data_walk);
}