Question

I have something similar to

Base.h

#ifndef BASE_H
#define BASE_H

class Base
{
virtual Base* createNew() = 0;
}

#endif

D.h

#ifndef D_H
#define D_H

#include "Base.h"

class D : public Base
{
virtual Base* createNew();
}

#endif

D.cpp

#include "D.h"
Base* D:createNew()
{
return new D();
}

main.cpp

typedef Base* (Base::*FP)(void);

#include "D.h"

void create(FP pointer)
{
//empty for now
}

int main()
{
create(&D::createNew); //This doesnt work =s?

}

I am extremely confused why this doesn’t work can anybody give me some advice on what I should be doing????

Ps. Sorry if the code doesnt run I put it there for example sakes just to show you what I was doing

Answer 1

There are numerous syntax problems in your code;

• Base::createNew() is private and virtual.
• Neither class declaration has a terminating ;.
• D:createNew() should be D::createNew().
  …

I think what you’re referring to though is that taking a member function pointer and passing it to a method won’t work.

The problem is that you’re taking a method that can only be called with a D and trying to pass it as a pointer to a function that can take a Base that is not necessarily a D. The reverse would work, (ie passing Base::createNew() to a function taking a D::createNew() since Base::createNew() always exists in a D, not the other way around)