Question

How do I declare a templated type that refers to itself?

template <class T = Animal> class Animal
{
public:
    T getChild ();
}

With this, I get a compiler error concerning a missing type specifier. I tried to forward-declare Animal, without success.

I am trying to impose a type constraint. A Lion can only have a Lion as a child, a Bear has a Bear, and so on.

EDIT

I’ll post part of the actual class. It is a template for classes that can appear in a linked list:

template <class T = Linked<T> > class Linked
{
private:
    T* m_prev;
    T* m_next;
}

I want to enforce that the class can only point to object of the same class (or a subclass).

Answer 1

The usual way to do something like a linked list is:

template <class T> class Linked
{
private:
    Linked<T>* m_prev;
    Linked<T>* m_next;
}

Does this work for you, and if not, what are you trying to accomplish that can’t be done this way?