Call child method from parent, when child is a template

Question

I have this college project where I have to create a BinarySearchTree class using templates. We have to read a file and create the tree depending of the data type in the file. I made a parent class for the tree called BST so I can use the tree without giving it a class type.

class BST{
    public:
        BST();
        ~BST();
}

And the tree

template <class T> class BinarySearchTree : public BST{
    public:
        void add(T val);
}

And I wanted to do this:

BST tree = BinarySearchTree<int>(); //just an example, it can be of any type
tree.add(5); //doesn't work

How can I call "add" from BST without giving a specific variable type?

Polymorphism requires indirection via pointer or reference. [A decent book](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list) would have told you as much. — StoryTeller - Unslander Monica, Nov 26 '17 at 16:38
So I have to use pointers? Like BST* tree = new BinarySearchTree(); ?? — JCAguilera, Nov 26 '17 at 16:41
Why don't you want to use BST without a class type? Also, you can use typename instead of class if you want primitive type too. — creekorful, Nov 26 '17 at 17:47

score 0 · Answer 1 · answered Nov 26 '17 at 16:45

0

You have to make a virtual method in the class BST and also make BST a template.

virtual void add(T val) = 0;

answered Nov 26 '17 at 16:45

Jake Freeman

1,700
1
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15

That's exactly what I didn't wanted to do, I cant make it a template, because I don't have the variable type – JCAguilera Nov 26 '17 at 16:46
@Juanky I don't know if you can. – Jake Freeman Nov 26 '17 at 16:56

score -1 · Answer 2 · answered Nov 26 '17 at 16:56

-1

Use CRTP(Curiously Reccursive/Reccuring Template Pattern) and Concept Pattern.

https://qiita.com/Riyaaaa_a/items/a9af401520f238f45b80

This is written in Japanese, however, it's interesting!

answered Nov 26 '17 at 16:56

yumetodo

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Call child method from parent, when child is a template

2 Answers2