Cocoa Import Controllers Model, Import Models Controller & # 8594; An exception

Question

Why isn't it possible in Cocoa for two classes to import each other? I tried the following code:

controller.h:

#import <Cocoa/Cocoa.h>
#import "Model.h"

@interface Controller : NSObject {
 Model *model;
}

@end

model.h:

#import <Cocoa/Cocoa.h>
#import "Controller.h"

@interface Model : NSObject {
 Controller *controller;
}

@end

which throws the following exceptions:

error: expected specifier-qualifier-list before 'Controller'
error: expected specifier-qualifier-list before 'Model'

Can someone explain why this is?

Thanks! xonic

+2

xon1c May 20 '10 at 12:31

2 answers

The solution for this is that: Model.h:

#import <Cocoa/Cocoa.h>
#import "Controller.h"

@class Controller;
@interface Model : NSObject {
 Controller *controller;
}

@end

And you are done with that

0

vodkhang May 20 '10 at 12:34

Paul lynch · Accepted Answer · 2010-05-20T12:35:07+0000

Explain why? No.

But the solution is to use @class declaration like this:

@class Model;
@interface Controller : NSObject {
 Model *model;
}
@end