Abstract base class and subclasses question.

[DeepT]

In short what I want to do is have an Abstract Base class call a method implemented in a subclass. I am sure I have done this at some point in the past, but I can't remember how. Anyway some sample code.

Abstract Base Class:

#pragma once

class CAbstractBase
{
public:
	CAbstractBase(void);
	~CAbstractBase(void);

protected:
	CString MyClassName;
	virtual void SetClassName()=0;
};

#include "StdAfx.h"
#include "AbstractBase.h"

CAbstractBase::CAbstractBase(void)
{
	SetClassName();
}

CAbstractBase::~CAbstractBase(void)
{
}

// If this method is commented out, I get a linker error, that this 
// symbol CAbstractBase::SetClassName(void) is missing
void CAbstractBase::SetClassName()
{
	MyClassName = "CAbstractBase";
}

SubClass:

#pragma once
#include "abstractbase.h"

class CSubClass :
	public CAbstractBase
{
public:
	CSubClass(void);
	~CSubClass(void);

	virtual void SetClassName();
};

#include "StdAfx.h"
#include "SubClass.h"

CSubClass::CSubClass(void)
{
}

CSubClass::~CSubClass(void)
{
}

void CSubClass::SetClassName()
{
	MyClassName = "CSubClass";
}

Program code:

CSubClass AClass;

		int T = 3;

I put a break point on the T = 3 assignment.

Anyway run as is, MyClassName == "CAbstractBase", not "CSubClass" which is the desired result. If I comment out the SetClassName() from the abstract base class, I get a linker error. I am not sure why since the base class will never be instanced because it is abstract. If I define the function, I get the wrong class name ( I kind of expected that to happen).

Is there a way to get the base class to call the sub-class method?

[D_Drmmr]

http://www.parashift.com/c++-faq-lit....html#faq-23.5

[Igor Vartanov]

CAbstractBase::CAbstractBase(void)
{
	SetClassName();
}

You should not call virtual method in base class constructor as the descendant is not constructed yet.