Thread: Singleton problems

I posted a question similar to this one before, but it seemed to die out.

Here is my problem: I have two classes using a singleton design pattern, and everything works fine. For our purposes one of the classes is called GameManager. The problem comes when I try to get the static instance of the GameManager from another class, let's say, Camera. I get a lot of parse errors before "*" from g++. Here are the parts of Camera and GameManager that i believe are causing problems:

GameManager.h

Code:

#ifndef AC_GAMEMANAGER_H_
#define AC_GAMEMANAGER_H_

#ifdef _WINDOWS
#include <windows.h>
#endif

#include <GL/gl.h>
#include <GL/glu.h>
#include <math.h>

#include "SDL.h"
#include "types.h"
#include "UIManager.h"
#include "Error.h"
#include "Scene.h"
#include "Keys.h"

class GameManager
{
    static GameManager *_instance;
    UIManager *uimanager;
    Scene scene;
    Keys keys;
    

    ac_int init(ac_void);
    ac_void loopGame(ac_void);
    ac_void renderScene(ac_void);
    
    GameManager() {}
public:
    static GameManager *instance(ac_void);

    ac_void beginGameLoop(ac_void);

    
    /* Get and Set */
     
     /**
     * @return the <code>Scene</code> object
     */   
    Scene getScene(ac_void) const { return scene; }
    
    /**
     * @return the <code>Keys</code> object
     */    
    Keys getKeys(ac_void) { return keys; }
};


#endif /* AC_GAMEMANAGER_H_ */

And the instance function for the GameManager:

Code:

GameManager *GameManager::_instance = 0;

GameManager *GameManager::instance()
{
    if (!_instance)
    {	
        _instance = new GameManager();
        _instance->init();
    }
    
    return _instance; 
}

Here are the problem parts in Camera:

Camera.h

Code:

#ifndef AC_CAMERA_H_
#define AC_CAMERA_H_

#include <GL/gl.h>
#include <GL/glu.h>

#include <stdio.h>
#include "SDL.h"
#include <math.h>

#include "UIManager.h"
#include "GameManager.h"
#include "MainFrame.h"
#include "Keys.h"
#include "Error.h"
#include "version.h"

class Camera {
/* ... */   
    
    GameManager *gameManager;
public:
/* ... */
};
#endif

And the places I use the gameManager in the Camera.cpp file:

Code:

Camera::Camera()
{
/* ... */
    
    gameManager = GameManager::instance();
}

/** And inside a movement function: */
    if(gameManager->getKeys().isActionDown("+forward")) {             

        MoveCamera(speed);              
    }

Here is the compiler output:

Code:

cd '/home/max/programming/c++/gl/angelchronicles/angelchronicles/debug' && WANT_AUTOCONF_2_5="1" WANT_AUTOMAKE_1_6="1" gmake -k -j1 
compiling angelchronicles.cpp (g++)
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/Camera.h:104: error: syntax error before `*' token
compiling LoadManager.cpp (g++)
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/Camera.h:104: error: syntax error before `*' token
compiling Game.cpp (g++)
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/Camera.h:104: error: syntax error before `*' token
compiling GameManager.cpp (g++)
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/Camera.h:104: error: syntax error before `*' token
compiling Camera.cpp (g++)
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/GameSceneRender.h:29: error: ' Camera' is used as a type, but is not defined as a type.
compiling Scene.cpp (g++)
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/GameManager.h:43: error: ' Scene' is used as a type, but is not defined as a type.
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/GameManager.h:63: error: parse error before `)' token
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/GameManager.h:68: error: ISO C++ forbids defining types within return type
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/GameManager.h:68: error: syntax error before `(' token
compiling GameSceneRender.cpp (g++)
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/Scene.h:51: error: syntax error before `*' token
*** Exited with status: 2 ***

Note: The problem goes away when I don't use GameManager in Camera.

Thanks alot, and if you need more code just ask. Any suggestions? Thanks!

>The problem goes away when I don't use GameManager in Camera.

then don't

Well that would be the easy way out, but then I don't get the functionality that I need. But is there a reason that this is happening? Am I approaching the singleton in the wrong way? Thanks.

try placing this line in GameManager.h instead of GameManager.cpp:

>> GameManager *GameManager::_instance = 0;

No change, I am afraid to say.

Could it possibly be that I have the first instance of GameManager created in a non-class as a global?

Here is my game.h file:

Code:

#ifndef AC_GAME_H_
#define AC_GAME_H_

#include "types.h"
#include "UIManager.h"
#include "GameManager.h"

extern UIManager *uimanager;
extern GameManager *gamemanager;

/**
 * Start the game by initializing the UIManager and the
 * GameManager, the two classes that handle the majority of
 * the game.  
 * @return any init codes
 */

ac_int startGame(ac_void);



#endif /* AC_GAME_H_ */

And Game.cpp

Code:

#include "Game.h"
#include "Error.h"

UIManager *uimanager;
GameManager *gamemanager;
/* Start the whole game.  Begin
 * by initializing the UIManager, then
 * the GameManager while will begin the event
 * loop.
 */
 
ac_int startGame(ac_void)
{
	//UIManager *uimanager;
	//GameManager *gamemanager;

	uimanager = UIManager::instance();
	gamemanager = GameManager::instance();

	gamemanager->beginGameLoop();

	return AC_INIT_SUCCESS;
}

>> Could it possibly be that I have the first instance of GameManager created in a non-class as a global?

that shouldn't matter. I even wrote a test application to duplicate the problem, but everything worked fine. not sure what the problem is...

Here is a package of all the code I have right now, maybe I am missing something else where...There are makefiles and everything included for linux, the win32 stuff is old in the package. Here is the link:
http://max.muffinpeddler.com/arch/an...200511.tar.bz2

Thanks so much for your help.

Have you tested if it works on any other compilers?

Another thing, but thats not a error I think, just me who dont know much about C++

but this sentence:

GameManager() {}

What does it do?
It looks to me like its calling the function but.. what does the two block-marks do? ( { } )
and why dont they need a ";" after them to finish the sentence?



EDIT:
Hmm..wait wait wait.. Its a function declaration?

The GameManager() {} just defines the default constructor, but it doesn't do anything. I may add to it later, but for now no.

Here is the vc++ 6 compiler output. Please disregard the opengl header errors, I need to add windows.h to the files:

Code:

--------------------Configuration: win32 - Win32 Debug--------------------
Compiling...
angelchronicles.cpp
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2143: syntax error : missing ';' before '*'
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2501: 'GameManager' : missing storage-class or type specifiers
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2501: 'gameManager' : missing storage-class or type specifiers
Error.cpp
Game.cpp
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2143: syntax error : missing ';' before '*'
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2501: 'GameManager' : missing storage-class or type specifiers
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2501: 'gameManager' : missing storage-class or type specifiers
LoadManager.cpp
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2143: syntax error : missing ';' before '*'
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2501: 'GameManager' : missing storage-class or type specifiers
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2501: 'gameManager' : missing storage-class or type specifiers
MainFrame.cpp
Prefs.cpp
UIManager.cpp
Camera.cpp
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\gamescenerender.h(29) : error C2146: syntax error : missing ';' before identifier 'camera'
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\gamescenerender.h(29) : error C2501: 'Camera' : missing storage-class or type specifiers
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\gamescenerender.h(29) : error C2501: 'camera' : missing storage-class or type specifiers
FreeType.cpp
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\freetype.cpp(364) : warning C4786: 'std::reverse_iterator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > const *,std::basic_string<char,std::char_traits<
char>,std::allocator<char> >,std::basic_string<char,std::char_traits<char>,std::allocator<char> > const &,std::basic_string<char,std::char_traits<char>,std::allocator<char> > const *,int>' : identifier was truncated to '255' characters in the debug 
information
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\freetype.cpp(364) : warning C4786: 'std::reverse_iterator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > *,std::basic_string<char,std::char_traits<char>,
std::allocator<char> >,std::basic_string<char,std::char_traits<char>,std::allocator<char> > &,std::basic_string<char,std::char_traits<char>,std::allocator<char> > *,int>' : identifier was truncated to '255' characters in the debug information
GameManager.cpp
c:\program files\microsoft visual studio\vc98\include\vector(39) : warning C4786: 'std::vector<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > >
 >::vector<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >' : identifier was truncated to '255' characters in the debug information
c:\program files\microsoft visual studio\vc98\include\vector(60) : warning C4786: 'std::vector<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > >
 >::~vector<std::basic_string<char,std::char_traits<char>,std::allocator<char> >,std::allocator<std::basic_string<char,std::char_traits<char>,std::allocator<char> > > >' : identifier was truncated to '255' characters in the debug information
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2143: syntax error : missing ';' before '*'
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2501: 'GameManager' : missing storage-class or type specifiers
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\camera.h(106) : error C2501: 'gameManager' : missing storage-class or type specifiers
GameSceneRender.cpp
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2144: syntax error : missing ';' before type 'void'
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2501: 'WINGDIAPI' : missing storage-class or type specifiers
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : fatal error C1004: unexpected end of file found
Keys.cpp
c:\documents and settings\max\desktop\angelchronicles\angelchronicles\src\keys.cpp(155) : warning C4800: 'int' : forcing value to bool 'true' or 'false' (performance warning)
LoadingRender.cpp
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2144: syntax error : missing ';' before type 'void'
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2501: 'WINGDIAPI' : missing storage-class or type specifiers
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : fatal error C1004: unexpected end of file found
MenuRender.cpp
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2144: syntax error : missing ';' before type 'void'
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2501: 'WINGDIAPI' : missing storage-class or type specifiers
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : fatal error C1004: unexpected end of file found
Scene.cpp
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2144: syntax error : missing ';' before type 'void'
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : error C2501: 'WINGDIAPI' : missing storage-class or type specifiers
c:\program files\microsoft visual studio\vc98\include\gl\gl.h(1152) : fatal error C1004: unexpected end of file found
version.cpp
Error executing cl.exe.

win32.exe - 27 error(s), 5 warning(s)

Code:

static GameManager *instance(ac_void); // ?
...
GameManager *GameManager::instance()
{
...

What is 'ac-void' out of curiosity? Is it defined somewhere as void or something else? Anyway, since there aren't errors regarding that, I presume it is.

My guess is that the problem has to do with the following errors:

/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/GameManager.h:43: error: ' Scene' is used as a type, but is not defined as a type.
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/GameManager.h:63: error: parse error before `)' token
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/GameManager.h:68: error: ISO C++ forbids defining types within return type
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/GameManager.h:68: error: syntax error before `(' token
compiling GameSceneRender.cpp (g++)
/home/max/programming/c++/gl/angelchronicles/angelchronicles/src/Scene.h:51: error: syntax error before `*' token

Which points strongly toward the problem being with Scene.

*edit*
What also makes me suspicious of that is that you are getting errors on lines 63 and 68 of a 52 line file (unless you didn't post all of GameManager.h).


Cheers,
Zach

Thanks I will look into it. I want to believe that the error is from Camera, a problem with my singleton implementation, but you may be right. If you don't mind, I gave a link above to the snapshot full code archive that has everything. Thanks alot for helping!

Edit: After scanning through Scene, I don't notice anything of worry.

And ac_void is typedef'ed as void.

Oh yea, and the "nonexistent" file line numbers are because I left out the common GPL heading stuff, which is about 15 lines

Heres the definition of the error I found online:

C2143: syntax error : missing ';' before '*'

If this error is followed by two C2501 errors then the problem is an undeclared class name within a pointer declaration.

For example, the declaration:

CClass *pObject;

will generate the above error message followed by a C2501 error message for 'CClass' and another C2501 message for 'pObject'. The problem is that the compiler isn't recognizing CClass as a valid class/type name. To correct the problem add a #include of the file containing the declaration of CClass (e.g., #include CClass.h)

The problem is, I have the proper header included...

static GameManager *_instance;
UIManager *uimanager;
Scene scene;
Keys keys;


ac_int init(ac_void);
ac_void loopGame(ac_void);
ac_void renderScene(ac_void);


Those functions and such... What happens to them when they arent defined in "public:" nor "private:"?
----------------------------------------------------------------------------
also, i dont know if it help, but have you tried to add
"using namespace std;" in your class-headers?

Those functions and such... What happens to them when they arent defined in "public:" nor "private:"?

They are automatically made private in a class, or public in a struct (so, private in this case).

Nothing appears to be wrong with the singleton implementation itself. And the initialization of _instance is perfectly fine going in the source file.