C++ 结合类继承和模板

Question

I have an assignment that involves inheritance and templates. I'm supposed to create a music player program and create several classes that inherit the functions of the linked list.

What I'm getting thrown off on, is inheriting a class template, to a class that is required to not have a template .

This is what I have so far. This is the class that is being inherited:

#ifndef LINKED_LIST_
#define LINKED_LIST_

#include <memory>

#include "ListInterface.h"
#include "Node.h"

template <typename ItemType>
class LinkedList : public ListInterface<ItemType> {

// ...

This is the class that's going to take the functions from the base class:

#ifndef DISC_
#define DISC_

#include <memory>
#include "LinkedList.h"

class Disc : public LinkedList {

// ...

I understand that I need to pass the template through the LinkedList declaration for the second block of code. However, I'm unsure how to do this. Something that I tried was:

template <typename ItemType>
class Disc : public LinkedList<ItemType> {

// ...

But would this declare the Disc class as a template? That's what my instructor told me. Thanks.

Answer 1

But would this declare the Disc class as a template?

Yes. If you want to have a type (not a template) that you can inherit from, you need to instantiate LinkedList . You can for example have a LinkedList of Disc s that would be LinkedList<Disc> . And Disc can be declared as

class Disc : public LinkedList<Disc> {};

Note that LinkedList<Disc> is not a template. It is a type like others, hence also Disc does not have to be a template. I had to do some guessing to choose the template parameter. I don't think Disc inheriting from a LinkedList<Disc> is a sound design. However, this is another possibility that would not be less odd:

class Disc : public LinkedList<int> {};

The point here is just to realize that LinkedList<int> is not a template, just like eg std::vector<int> is not a template.