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

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.

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.

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

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