Namespace problems

Namespace problems

raycrasher

Member #6,683

December 2005

Take the following:

1 
2// File: engine.h
3#header guard
4#include "graphics.h"   // for the camera below
5 
6// adding 'class Camera;' here reduced the errors somewhat, but i think its wrong, w/o the namespace and everything.
7 
8namespace Engine {
9    class Object {
10        ...
11        virtual void draw(Graphics::Camera &cam) {};
12    };
13}
14 
15// File: graphics.h
16#header guard
17#include "engine.h" // for Object list below
18 
19// adding 'class Object;' here reduced the errors somewhat, but i think its wrong, w/o the namespace and everything.
20 
21namespace Graphics {
22    class Camera {
23        Engine::Object *focus;
24    };
25}

The problem is, I get plenty of compile errors - "Undefined: Engine" in graphics.h and/or "Undefined: Graphics" in engine.h. I finally solved the problem by limiting the contents of my namespaces to functions and variables, but no class/struct defs. I'm just wondering what caused the errors.

aj5555

Member #9,033

September 2007

circular dependancies.

which means you have a bad design.

circular dependancies -> which came first chicken or the egg?

OnlineCop

Member #7,919

October 2006

aj5555 said:

circular dependancies -> which came first chicken or the egg?

The egg, of course! With the "evolution theory", the last "mutation" of the chicken's species was transferred into the now-layed egg. The egg, being a mutant of the "almost chicken" parent, can now officially be called "a chicken". Once it is hatched, it can be considered a full-fledged chicken, and when it mates with the "almost a chicken" species, natural selection allows it to keep its "chicken" classification and life is good. Colonel Sanders is soon spotted on the horizon.

Neil Black

Member #7,867

October 2006

Quote:

Colonel Sanders is soon spotted on the horizon.

And almost-chicken tells chicken, "Good luck, loser!" and runs off leaving chicken to its horrible (but delicious) fate. Ironically, almost-chicken was then eaten by a saber-toothed tiger, which sucks because, had almost-chicken survived, we would have had a food source that did not, in fact, taste like chicken.

Bob

Free Market Evangelist

September 2000

Simply forward-declare your classes.

// In engine.h
namespace Graphics {
    class Camera;
}

Hope this helps.

--
- Bob
[ -- All my signature links are 404 -- ]

raycrasher

Member #6,683

December 2005

Yes, you're right. It was a crappy design, so I overhauled the code, used singletons for Engine and Graphics and whatnot. It compiles okay now, and looks more readable, too. Thanks.

Now, if I can only make OpenLayer run faster on my crappy S3 ProsavageDDR...

GullRaDriel

Member #3,861

September 2003

Quote:

Now, if I can only make OpenLayer run faster on my crappy S3 ProsavageDDR...

You can not ask a donkey to run as fast as a horse.

"Code is like shit - it only smells if it is not yours"
Allegro Wiki, full of examples and articles !!

raycrasher

Member #6,683

December 2005

Oh well. New card, then. Or strap a rocket booster to teh donkey.