C++ compilers bitch when I do this

Say I have two .cpp files and their corresponding .h files.  For the sake of brevity I'll leave it to just the parts that cause trouble:

==============================

//-------
//actor.h
//-------

#include "mapdef.h"

class Actor {
 ...
 private:
    Level *parent_level;
 ...
};
==========================

// ----------
// mapdef.h
// ----------
#include "actor.h"

class Level {
  ...etc etc...
 
  private:
     Actor *actors;   // I'd use a linked list, vector, or something more flexible in the actual code
...etc etc blah blah blah...
};

==========================================================

I also use #ifdef _ACTOR_H blah blah blah to make sure header files are never loaded more than once in the preprocessor (which causes compilation to terminate w/ error), like good programming practice.

Anyway, because of the way the preprocessor does things, this causes problems.  Say a .cpp file does an #include "mapdef.h".  The Level class refers to an Actor, and the mapdef.h itself #includes actor.h so it can "know" what an Actor is.

...but the compiler gets confused because then it looks in Actor class and it refers to a Level object... but Level isn't finished being defined yet.  Because these two classes refer to each other in some way for necessary objects/pointers/etc, the compiler shits.

I do find that adding "class" before objects fixes it:

class Actor {
  (blah blah blah)
  private:
     class Level *parent_level;
  (blah blah blah)
};

class Level {
  (blah blah blah)
  private:
     class Actor actors[200];
  (blah blah blah)
};

But I've never seen this done before in anyone else's code, and I'm not sure this is "kosher" by ANSI/ISO standards even though gcc and Visual C++ allow it.

The way I fix it... am I doing it right?  Or is there a better, less iffy way?

You can do it the way you did, or you could put some class Actor; and class Level; before the definition of the opposite classes. (I think I got the syntax right)

>>1
What you are doing is a forward definition of a class.  You would normally do it by putting something like "class Actor;" around the top of the file like >>2 said all awkwardly.  However, if you are using two classes in each other, you really need to analyze the structure of your program and make sure that it is really necessary because this is bad OOP.

Yeah, it's not best practices if you make anything useful with your classes.

>>3
because enterprise scalable solutions require 100 classes in each other, amirite?

YOU ARE NOW THINKING MANUALLY

right its just not going to give   your program a   BETTER ONE LOLOLOLOLOL   Quite true This   is at a   cat riding a   bus and suddenly   a black snake   head with the   most retarded of   questions a recommendation   of withdrawal note   the rest of   them I do   real work in   a world like.

beware the army of 12 year old autistics

10 Name: Anonymous 2011-06-16 2:08

[over][under]EXPERT BBCODE PROGRAMMER[/under][/over]