Question

I have next class and try to declare member function which will return pointer to a that type but next code

template<class Key, int b> class b_plus_tree_inner_node {
  auto split() -> decltype(this) {}
};

gives me such error

invalid use of ‘this’ at top level

can i do it in another way, i now about existence of typedef, but may be its possible with decltype?

EDITED:

i want to accomplish this:

b_plus_tree_inner_node<Key, b>* split() {...}

Answer 1

If you want a member function declare it inside the class:

template<class Key, int b> class b_plus_tree_inner_node {
   b_plus_tree_inner_node* split(){}
   // also valid:
   //b_plus_tree_inner_node<Key, b>* split(){}
};

If you want a non-member function, make it a template:

template<class Key, int b>
b_plus_tree_inner_node<Key, b>* split(){}

The standard does allow you to write auto split() -> decltype(this) {} but GCC 4.6 doesn’t support it yet (the trunk of GCC 4.7 does).