Question

Here is basically what my class layout is:

GameDriver.h:

#ifndef GAMEDRIVER_H
#define GAMEDRIVER_H
#include "CameraSystem.h"

class CameraSystem; //Forward declaration

class GameDriver {
    //Stuff
};

#endif

CameraSystem.h:

#ifndef CAMERASYSTEM_H
#define CAMERASYSTEM_H
#include "Tickable.h"

class GameDriver;
class CameraSystem: public Tickable { //Complains here
    //Stuff
};

#endif

Tickable.h:

#ifndef TICKABLE_H
#define TICKABLE_H
#include "GameDriver.h"
class GameDriver;
class Tickable {
    //Stuff
};

#endif

Here is the error I get:

CameraSystem.h:9 error: expected class-name before '{' token

Forward declaring Tickable does not work either. Any help? Thanks in advance.

Answer 1

You can’t resolve such circular dependencies. However, you’ve got the solution (partially):

I.e. instead of including a header, just use a forward declaration. If you do this right, there shouldn’t be any issues. However, try to group your program into logical elements/groups and only add cross-references if they’re requied (e.g. the game has to know about and access the camera, but the camera shouldn’t have to access the game system as a whole).