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From: thc@cs.brown.edu (Thomas Colthurst)
Newsgroups: comp.lang.c++
Subject: Multiple Inheritance Problem
Message-ID: <74462@brunix.UUCP>
Date: 3 May 91 22:26:11 GMT
Sender: news@brunix.UUCP
Organization: Brown Computer Science Dept.
Lines: 70


I've got the following object inheritance hierarchy:


                                Object
                                /    \
                               /      \
                             Line    Dependent
                               \       /
                                \     /
                              DependentLine

or in code,

class Object {
public:

  Object();
  ~Object();

   virtual void Draw() = 0;

   virtual void Update() = 0;

   virtual Object* Dup() = 0;

}

class Line: public virtual Object {
public:

   Line();
   ~Line();

   void Draw();

}

class Dependent: public virtual Object {
public:

  Dependent();
  ~Dependent();

  void Update();

}


class Dependent: public Line, public Dependent {
public:

  DependentLine();
  ~DependentLine();

  Object *Dup() { return( (new DependentLine) ); }; // error here

}



Sun CC version 2.1 gives me an error on the line
marked above, saying

"./ChildrenObjs.H", line 30: error: `new' of abstract class DependentLine

What am I doing wrong?

Thanks,
-Thomas C