Re: Help with solving seemingly mutually exclusive problems please

From:
 Zilla <zilla62@bellsouth.net>
Newsgroups:
comp.lang.c++
Date:
Fri, 19 Oct 2007 15:19:04 -0700
Message-ID:
<1192832344.459923.259290@q5g2000prf.googlegroups.com>
On Oct 19, 6:10 pm, Zilla <zill...@bellsouth.net> wrote:

On Oct 19, 6:01 pm, "Victor Bazarov" <v.Abaza...@comAcast.net> wrote:

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
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask- Hide quoted text -

- Show quoted text -


Ah, the _name value, but that's beside the point - I don't care what
the names are - make them same. Look at the pointer values that I
print out. TY- Hide quoted text -

- Show quoted text -


Ok here's output for correcte _name cut & paste error

With cmds->cmd=cmds1->cmd; uncommented...
cmds->cmd: ACmd 0x0x40004820 ,cmds1->cmd: BCmd 0x0x40004840
cmds->cmd: BCmd 0x0x40004840 ,cmds1->cmd: BCmd 0x0x40004840
equal

With *cmds->cmd=*cmds1->cmd; uncommented
cmds->cmd: ACmd 0x0x40004820 ,cmds1->cmd: BCmd 0x0x40004840
cmds->cmd: BCmd 0x0x40004820 ,cmds1->cmd: BCmd 0x0x40004840

Again, in the first case, value AND content of cmds->cmd changed, but
if passed. In the seconde case, ONLY content changed, bugt if fails.

I want ONLY content change, and passing if. TY again.

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