Re: Help with solving seemingly mutually exclusive problems please

From:
"Victor Bazarov" <v.Abazarov@comAcast.net>
Newsgroups:
comp.lang.c++
Date:
Fri, 19 Oct 2007 18:01:51 -0400
Message-ID:
<ffb9gh$khv$1@news.datemas.de>
Zilla wrote:

On Oct 19, 5:02 pm, red floyd <no.s...@here.dude> wrote:

Zilla wrote:

I put everything in one file for ease of use; also I have #include
<*.h> files instead of the <*> since my compiler is pre-ANSI C so it
needs the .h

#include <iostream.h>
#include <iomanip.h>
#include <string.h>

class Cmd {
public:
   virtual ~Cmd() {}
   char* printCmd()
   {
      return _name;
   }
protected:
   Cmd() {}
   char _name[16];
};

class ACmd : public Cmd {
public:
   static Cmd* getInstance()
   {
      if (!_instance) {
         _instance=new ACmd;
      }
      return _instance;
   }
   ~ACmd() {}
private:
   ACmd()
   {
      strcpy(_name, "ACmd");
   }
   static Cmd* _instance;
};

class BCmd : public Cmd {
public:
   static Cmd* getInstance()
   {
      if (!_instance) {
         _instance=new BCmd;
      }
      return _instance;
   }
   ~BCmd() {}
private:
   BCmd()
   {
      strcpy(_name, "ACmd");


I suspect your error lies here.

   }
   static Cmd* _instance;
};

typedef struct {
   Cmd* cmd;
} CmdS;- Hide quoted text -


- Show quoted text -- Hide quoted text -

- Show quoted text -


How? ACmd and BCmd are singletons, and that's how one codes one. See
Design Patterns book.


You're thinking so much outside the box that you aren't seeing the
obvious mistake. Hint: it's a copy-and-paste error. Look at it again
and this time really try to see what the function is and what it needs
to do (what every statement needs to do), and what it actually does
(and what the effect of it is).

V
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