Circular Dependencies / Incomplete Types

Question

In C++, I have a problem with circular dependencies / incomplete types. The situation is as follows:

Stuffcollection.h

#include \"Spritesheet.h\";
cl         


        

Answer 1

You should include Spritesheet.h in Stuffcollection.cpp
Just use forward declaration in the header file not the cpp file, that solves the circular dependency of the header file. The source file has no circular dependency actually.

Stuffcollection.cpp needs to know the complete layout of class Spritesheet(because you dereference it), So you need to include the header which defines the class Spritesheet in that file.

From your previous Q here, I believe that class Stuffcollection is used in the class declaration of Spritesheet header file and hence the above proposed solution.

Answer 2

Spritesheet.h doesn't need to include Stuffcollection.h, since no Stuffcollection is used in the class declaration of Spritesheet. Move that include line to Spritesheet.cpp instead and you should be fine.

Answer 3

Use this form for your nested includes:

Stuffcollection.h

#ifndef STUFFCOLLECTION_H_GUARD
#define STUFFCOLLECTION_H_GUARD
class Spritesheet;
class Stuffcollection {
  public:
  void myfunc (Spritesheet *spritesheet);
  void myfuncTwo ();
};
#endif

Stuffcollection.cpp

#include "Stuffcollection.h"
#include "Spritesheet.h"

void Stuffcollection::myfunc(Spritesheet *spritesheet) {
  unsigned int myvar = 5 * spritesheet->spritevar;
}

void Stuffcollection::myfuncTwo() {
  //
}

Spritesheet.h

#ifndef SPRITESHEET_H_GUARD
#define SPRITESHEET_H_GUARD
class Spritesheet {
  public:
  void init();
};
#endif

Spritesheet.cpp

#include "Stuffcollection.h"
#include "Spritesheet.h"

void Spritesheet::init() {
  Stuffcollection stuffme;
  myvar = stuffme.myfuncTwo();
}

General rules I follow:

• Don't include an include from an include, dude. Prefer forward declarations if possible.
  • Exception: include system includes anywhere you want
• Have CPP include everything it needs, not relying upon H recursively including it files.
• Always use include guards.
• Never use pragma