Can't instantiate absstract class

[lucky6969b]

Sorry, two more questions

 #ifndef PERFECTSIM_PARSER
#define PERFECTSIM_PARSER

 
 

#include <string>
#include <d3dx9.h>
#include <sstream>
#include <iostream>

#include "tinyxml\tinyxml.h"


using namespace std;

template<class T>
class GetValue
{
protected:
	virtual T get(TiXmlNode* pParent);
	virtual T get_attribs(TiXmlNode* pParent) = 0;
};

 
 
class GetVector3 : public GetValue<D3DXVECTOR3>
{
public:
	virtual D3DXVECTOR3 get(TiXmlNode* pParent);
	virtual D3DXVECTOR3 get_attribs(TiXmlElement *element);
	D3DXVECTOR3 get_vector3(TiXmlElement *element);
	
};

template<class T>
T GetValue<T>::get(TiXmlNode* pParent)
{
	T attr;
	if ( !pParent ) return attr;

	TiXmlNode* pChild;
	TiXmlText* pText;
	int t = pParent->Type();
	
	 
 

	switch ( t )
	{
	case TiXmlNode::TINYXML_DOCUMENT:
	 
		break;

	case TiXmlNode::TINYXML_ELEMENT:
	 
		 attr =get_attribs(pParent->ToElement());
		break;

	case TiXmlNode::TINYXML_COMMENT:
	 
		break;

	case TiXmlNode::TINYXML_UNKNOWN:
		 
		break;

	case TiXmlNode::TINYXML_TEXT:
		pText = pParent->ToText();
		 
		break;

	case TiXmlNode::TINYXML_DECLARATION:
		 
		break;
	default:
		break;
	}
	 
	for ( pChild = pParent->FirstChild(); pChild != 0; pChild = pChild->NextSibling()) 
	{
		get( pChild );
	}

	return attr;

}

 
#endif

// tutorial demo program
#include "stdafx.h"
#include "Parser.h"

 
/////////////////////////////////////
///

D3DXVECTOR3 GetVector3::get(TiXmlNode* pNode)
{
	return GetValue::get(pNode);
}

 
D3DXVECTOR3 GetVector3::get_vector3(TiXmlElement* pElement)
{

	return get_attribs(pElement);
	 
}

D3DXVECTOR3 GetVector3::get_attribs(TiXmlElement* pElement)
{
	
	if ( !pElement ) return D3DXVECTOR3();

	GetValue::get(pElement);
	D3DXVECTOR3 v;

	pElement->QueryFloatAttribute("X", &v.x);
	pElement->QueryFloatAttribute("Y", &v.y);
	pElement->QueryFloatAttribute("Z", &v.z);

	return v;


}

1) Can't instantiate abstract class of GetVector3.
2) Don't you think the coding is very redundant ?

Any help please?
Thanks
Jack

[nuzzle]

1) Can't instantiate abstract class of GetVector3.

Just make sure all virtual methods have concrete implementations.

[D_Drmmr]

2) Don't you think the coding is very redundant ?

The design seems very complicated. It's not clear to me what you want to achieve. Why do you have a template base class? Why does it have only protected virtual functions?

You should first think about what you want your program to do. Then think about a (class) design that can fulfill those requirements and only then you should start coding.

[Yves M]

When you overwrite a pure virtual function, it has to have the same signature. Otherwise you haven't actually overwritten it, you just have declared an unrelated virtual function.

virtual T get_attribs(TiXmlNode* pParent) = 0;
...
D3DXVECTOR3 GetVector3::get_attribs(TiXmlElement* pElement)

So the base class's get_attribs(TiXmlNode* pParent) function is still not defined in the derived class GetVector3 and hence the compiler says that the class contains undefined virtual functions and is an abstract class.