Can't instantiate absstract class

Sorry, two more questions

Code:

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#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

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Code:

---


// 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;


}

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

Any help please?
Thanks
Jack

Quote:

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Originally Posted by lucky6969b

1) Can't instantiate abstract class of GetVector3.

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Just make sure all virtual methods have concrete implementations.

Quote:

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Originally Posted by lucky6969b

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

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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.

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.

Code:

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

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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.