如何为以指针作为模板类型的链表节点定义模板类

Question

How to define a node template for a linked list? I also want to keep the pointer type as template parameter so that I can change it to unique_ptr or shared_ptr depends on what available.

template<typename T, typename NodePtr>
struct node{
    T data;
    NodePtr parent = nullptr;
};

The question is that how to initiate this class so that Nodeptr will be shared_ptr < Node <T ,what?> > type?

Answer 1

The "Simplest" solution I can think of is a variadic template template parameter:

template<class T,template<class ...> class PTR_T>
struct Node {
    T data;
    PTR_T<Node> parent{nullptr};
};

This works with both unique_ptr and shared_ptr like this:

Node<int,std::shared_ptr> roots;
Node<int,std::unique_ptr> rootu;

As suggested by yourself, you'd have to introduce a type alias, if you want to use raw pointers:

template<class T> using raw_ptr = T*;

Answer 2

You only need to pass parameter T :

template <typename T>
struct node
{
  T data;
  node<T> * parent;
}