Is there any way to create a pair of template class containing each other?

Question

I wanna do sth like this:

A.hpp:

template <class B>
class A{
  B* B;
};

B.hpp:

template <class A>
class B{
  A* a;
};

and it always fails..

You have a circular dependency. You should also consider changing the template typenames so they don't conflict with the actual class names. — Cory Kramer, May 06 '20 at 13:25
Ntice that `B` in `template class A;` is unrelated to `class B` as between `int n = 42; void f(int n);`, So your code, as-is compile, `class A` and `B` are class with similar definition (only name of member change). — Jarod42, May 06 '20 at 13:55

Jarod42 · Answer 1 · 2020-05-06T13:51:56.913

1

You might use template template parameter (if appropriate):

template <template <typename> class C>
class A{
  C<A>* B;
};

template <template <typename> class C>
class B{
  C<B>* a;
};

So, A<B> and B<A> are both valid types.

edited May 06 '20 at 13:51

answered May 06 '20 at 13:30

Jarod42

1 Answers1