Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!apple!bionet!agate!ucbvax!hplabs!hp-pcd!hplsla!jima
From: jima@hplsla.HP.COM (Jim Adcock)
Newsgroups: comp.lang.c++
Subject: Re: constructors for virtual base classes
Message-ID: <6590185@hplsla.HP.COM>
Date: 6 Jul 89 23:35:53 GMT
References: <1429@masscomp.UUCP>
Organization: HP Lake Stevens, WA
Lines: 50

//It seems to me that the constructor for "common" will be called twice.
//What am I doing wrong? - Keith

//Maybe nothing -- I made the following slight mods to your example and
//under my compiler common() only gets called once.  Is this what you
//wanted?  See Lippman pages 360-370.

#include <stdio.h>

class common
{
public:
  common () {printf("common ");}
};

class virtual_1 : virtual public common
{
public:
  virtual_1 () : common () {printf("virtual_1 ");}
};

class virtual_2 : virtual public common
{
public:
  virtual_2 () : common () {printf("virtual_2 ");}
};


class both : public virtual_1, public virtual_2
{
public:
  both () : virtual_1 (), virtual_2 () {printf("both ");}
};

main()
{
  common c; 		printf("\n");
  virtual_1 v1;		printf("\n");
  virtual_2 v2;		printf("\n");
  both b;		printf("\n");
}


/************* gives this output ***************/


common 
common virtual_1 
common virtual_2 
common virtual_1 virtual_2 both