Question

I have a question about inheritance and template methods. Suppose I have this two classes

class Base
{
public:
   template<typename T>
   void print(const T& s) {std::cout << "Base (templated) prints " << s << "\n";}
   virtual void print(int i) {std::cout << "Base prints " << i << "\n";}
};

class Derived : public Base
{
public:
   void print(int i) {std::cout << "Derived prints " << i << "\n";}
}

int main()
{
   Derived d;
   d.print(3);     // works fine
   std::string s = "hi";
   d.print(s);  // does not compile
   return 0;
}

The compiler tells me ”no matching function for call to ‘Derived::print(std::string&)’’.
But Derived, inheriting from Base, should also allow a call to the template method print(..), no?

Things are also weird cause if I don’t define a method “print” in the derived class, then everything works fine and the compiler calls the base class template method.

Things work fine also if I define the template method also in the derived class, which calls the base class one, but that does not seem right to me…

Thanks for your help.

Answer 1

Declaring a function in the derived class hides any functions with the same name in the base class. You can unhide them with a using declaration:

class Derived : public Base
{
public:
    // Add this
    using Base::print;

    void print(int i) {std::cout << "Derived prints " << i << "\n";}
}