Templates and classes

I keep getting bizzare errors when trying to compile the following code..These are standard template classes.


I have the following two files:

BraidedNode.cpp

Code:

---

#include "BraidedNode.h"

template<class T> BraidedNode<T>::BraidedNode(T val) :
  TreeNode<T>(val)
{
}

template<class T> *BraidedNode<T>::rchild(void) :
  TreeNode<T>(val)
{
  return (BraidedNode<T>*)_rchild;
}

template<class T> *BraidedNode<T>::lchild(void) :
  TreeNode<T>(val)
{
  return (BraidedNode<T>*)_lchild;
}


template<class T> *BraidedNode<T>::next(void) :
  TreeNode<T>(val)
{
  return (BraidedNode<T>*)_next;
}

template<class T> *BraidedNode<T>::prev(void) :
  TreeNode<T>(val)
{
  return (BraidedNode<T>*)_prev;
}

---

BraidedNode.h

Code:

---

#ifndef _BraidedNode_h
#define _BraidedNode_h

#include <stdio.h>
#include "Node.h"
#include "TreeNode.h"

template<class T>class BraidedNode : public Node, public TreeNode<T>
{
  public:
  BraidedNode(T);
  BraidedNode<T> *rchild(void);
  BraidedNode<T> *lchild(void);
  BraidedNode<T> *next(void);
  BraidedNode<T> *prev(void);
  //friend class BraidedSearchTree<T>;
};

---

and the error I get is:

Code:

---

BraidedNode.cpp:8: error: ISO C++ forbids declaration of ‘rchild’ with no type
BraidedNode.cpp:8: error: prototype for ‘int* BraidedNode<T>::rchild()’ does not match any in class ‘BraidedNode<T>’
BraidedNode.h:12: error: candidate is: BraidedNode<T>* BraidedNode<T>::rchild()
BraidedNode.cpp:8: error: template definition of non-template ‘int* BraidedNode<T>::rchild()’
BraidedNode.cpp: In member function ‘int* BraidedNode<T>::rchild()’:

---

Code:

---

template<class T> BraidedNode<T> *BraidedNode<T>::rchild(void) :
  TreeNode<T>(val) // part in red is wrong
{
  return (BraidedNode<T>*)_rchild; // The cast is unnecessary
}

---

And same for the others.

Some advice: don't "copy and paste" bits... type them. You've copied over the constructor initialization list and forgot to add the return type.

Soma

whoops, bit of a typo: the error I have now is:

BraidedNode.cpp: In member function ‘BraidedNode<T>* BraidedNode<T>::rchild()’:
BraidedNode.cpp:11: error: ‘_rchild’ was not declared in this scope
BraidedNode.cpp: In member function ‘BraidedNode<T>* BraidedNode<T>::lchild()’:
BraidedNode.cpp:17: error: ‘_lchild’ was not declared in this scope

rchild should be defined....any ideas....

What is your current code?

Code:

---

#include "BraidedNode.h"


template<class T> BraidedNode<T>::BraidedNode(T val)
: TreeNode<T>(val)
{
}

template<class T>
BraidedNode<T> *BraidedNode<T>::rchild(void)
{
  return (BraidedNode<T>*)_rchild;
}

template<class T>
BraidedNode<T> *BraidedNode<T>::lchild(void)
{
  return (BraidedNode<T>*)_lchild;
}

template<class T>
BraidedNode<T> *BraidedNode<T>::next(void)
{
  return (BraidedNode<T>*)_next;
}

template<class T>
BraidedNode<T> *BraidedNode<T>::prev(void)
{
  return (BraidedNode<T>*)_prev;
}

---

and

Code:

---

#ifndef _BraidedNode_h
#define _BraidedNode_h

#include <stdio.h>
#include "Node.h"
#include "TreeNode.h"

template<class T>class BraidedNode : public Node, public TreeNode<T>
{
  public:
  BraidedNode(T);
  BraidedNode<T> *rchild(void);
  BraidedNode<T> *lchild(void);
  BraidedNode<T> *next(void);
  BraidedNode<T> *prev(void);
  //friend class BraidedSearchTree<T>;
};



#endif

---

Note that it's usually not a good idea to put templates into .cpp files. As to why, I don't have the link, but I'm sure someone else does.
Templates go into header files.

So... you really don't have any data members? Or are they inherited?

Soma

Quote:

---

Note that it's usually not a good idea to put templates into .cpp files. As to why, I don't have the link, but I'm sure someone else does.
Templates go into header files.

---

One such explanatory link would be: Why can't I separate the definition of my templates class from it's declaration and put it inside a .cpp file?

That said, that is not (yet) the problem.

Quote:

---

So... you really don't have any data members?

---

Inherited non-private data members, perhaps? Or maybe they are actually private, thus they are not in scope, as the error message says.

Quote:

---

Originally Posted by phantomotap

So... you really don't have any data members? Or are they inherited?

Soma

---

Should be inheriting from the Node class and Tree Node class, which are as follows:

Code:

---

template<class T> class TreeNode {
protected:
  TreeNode *_lchild;
  TreeNode *_rchild;
  T val;
public:
  TreeNode(T);
  virtual ~TreeNode(void);
  //friend class SearchTree<T>;
  //friend class BraidedSearchTree<T>;
};

---

and as follows....

Code:

---

class Node {
protected:
  Node *_next;
  Node *_prev;
public:
  Node(void);
  virtual ~Node(void);
  Node *next(void);
  Node *prev(void);
  Node *insert(Node*);
  Node *remove(void);
  void splice(Node*);
};

---

Any ideas?

Add 'this->' to every reference of an inherited data member.

Add 'this->' to every reference of an inherited method (function).

Add 'base_type::' to every reference of an inherited 'typedef'.

Add 'base_type::' to every reference of an inherited nested class.

Soma

Quote:

---

Add 'this->' to every reference of an inherited data member.

---

Oh yes, good catch.

Code:

---

template<class T> class TreeNode {
protected:
  TreeNode *_lchild;
  TreeNode *_rchild;
  T val;
public:
  TreeNode(T);
  virtual ~TreeNode(void);
  //friend class SearchTree<T>;
  //friend class BraidedSearchTree<T>;
};

---

I have added the following base class, but now I get the messages below

Code:

---

template<class T> BraidedNode<T>::BraidedNode(T val)
: TreeNode<T>(

val)
{
}

template<class T>
BraidedNode<T> *BraidedNode<T>::rchild(void)
{
  return (BraidedNode<T>*)TreeNode::_rchild;
}

template<class T>
BraidedNode<T> *BraidedNode<T>::lchild(void)
{
  return (BraidedNode<T>*)TreeNode::_lchild;
}

template<class T>
BraidedNode<T> *BraidedNode<T>::next(void)
{
  return (BraidedNode<T>*)_next;
}

template<class T>
BraidedNode<T> *BraidedNode<T>::prev(void)
{
  return (BraidedNode<T>*)_prev;
}

---

BraidedNode.cpp: In member function ‘BraidedNode<T>* BraidedNode<T>::rchild()’:
BraidedNode.cpp:12: error: expected primary-expression before ‘*’ token
BraidedNode.cpp:12: error: expected primary-expression before ‘)’ token
BraidedNode.cpp:12: error: expected ‘;’ before ‘TreeNode’
BraidedNode.cpp:12: error: ‘template<class T> class TreeNode’ used without template parameters

Tell me, if you were walking along with a friend and he/she pointed to the sky, would you look at his finger? (Read ALL of what I wrote; don't assume things by skimming it.)

Soma