C++ equivalent of using for a java parameter/return type

Question

In java, to make a function that returns an object that is the same type as a parameter and extends a certain class, I would type:

Answer 1

We can use enable_if here if you have C++11 or higher available to you

template::value>::type* = nullptr>
T Foo(T bar)
{
    return T();
}

For example:

class MyClass
{
public:
    int a = 1;
};

class Derived : public MyClass
{
public:
    int b = 2;
};

class NotDerived
{
public:
    int b = 3;
};

template::value>::type* = nullptr>
T Foo(T bar)
{
    return T();
}

int main()
{
    Derived d;
    NotDerived nd;
    std::cout << Foo(d).b << std::endl;; // works
    //std::cout << (Foo(nd)).b << std::endl;; //compiler error

    return 0;
}

Live Demo