How do I pass a C++11 random number generator to a function?

Question

Do they all inherit from a base class? Do I have to use templates?

(I am referring to these http://www.codeguru.com/cpp/cpp/cpp_mfc/stl/article.php/c15319/)

Answer 1

They don't all inherit from a base (which is a little surprising), but it doesn't matter because that's not how C++ functors work.

For arbitrary RNGs of a single given type, you got it right as (now) posted.

If you mean, how do I define a function which accepts any random number generator as an argument.

template< class RNG > // RNG may be a functor object of any type
int random_even_number( RNG &gen ) {
    return (int) gen() * 2;
}

You don't need to use any more templates than this, because of type deduction.

---

Defining one function to accept different RNG's is trickier because semantically that requires having a common base type. You need to define a base type.

struct RNGbase {
    virtual int operator() = 0;
    virtual ~RGNBase() {};
};

template< class RNG >
struct SmartRNG : RNGBase {
    RNG gen;

    virtual int operator() {
        return gen();
    }
};

int random_even_number( RNGBase &gen ) { // no template
    return (int) gen() * 2; // virtual dispatch
}