OOP / Import problem: Access to children from super class?

[prtfx]

Hi,

I want to have simple messaging between two classes. My problem is, that class TestB (child) already extends class TestA (parent/super class).

Therefore TestB imports TestA.h. So simple so good. But now I want to create a TestB member in TestA ... and I need to import TestB.h in TestA.h

Now the compiler starts complaining ... does anybody know how I can exchange messages between my super-class and its chidren from both sides?

I dont see any bad OOP style here, so it should be possible ...?

Thanks.

[smasher]

You have a "loop" in your headers where a includes b includes a. You can break it using the @class directive, which "forward declares" a class.

in A.h:
@class B
in A.m:
#import "B.h"

in B.h:
@class A
in B.m:
#import "A.h"

With the @class directive you don't get any information about the methods or properties of the other object, but you do not need them to compile the header anyway. You usually do need that information when compiling the .m file, though, so the .m file gets the #import.

[prtfx]

Ok, got it. I need to refer to the singleton pattern for TestA. Then it works fine, although it was not really what I intended first.

[prtfx]

Thanks smasher ... that's exactly what I've searched for.

However, I found that the Singleton fits better to my design. But it's good to know the exact reason why it failed .. fine!