Re: Objective-C++ Instance Variables

> I'm trying to bridge between my Cocoa App and my C++ framework via
> Objective-C++. Apparently I can't have C++ objects as instance
> variables in my ObjC class because they contain virtual methods. Also,
> I don't appear to be able to include my C++ header files in by ObjC
> header file; they work fine if I include them in my implementation
> file (.mm).
> 
> How should I create my C++ objects and use them within my ObjC class
> (over it's lifetime)?  Perhaps I should be doing this a different way?
> What I have is a C++ framework compiled into a dylib. I include the
> headers in my .mm and link in the dylib.


What I've done is create a pointer in my Objective C class which points 
to my C++ class:

@[EMAIL PROTECTED]
 ObjCClass : NSObject
{
   CPPClass *fPtr;
}

- (id)init;
- (void)dealloc;

@[EMAIL PROTECTED]
 ObjCClass

- (id)init
{
   self = [super init];
   if (self) {
      fPtr = new CPPClass;
   }
   return self;
}

- (void)dealloc
{
   if (fPtr) delete fPtr;
   [super dealloc];
}

@[EMAIL PROTECTED]
 that this implies that you either #include the C++ header in your 
Objective C header, or you need to declare the CPPClass in the Objective 
C header as a anonymous C++ class. In either case, this means you can 
only #im****t your Objective C header in a .mm file.

There are some places where things can get a little mind-bending, by the 
way; in a few places in my code I've written things like:

   std::map<int32_t,MyStruct> array;
   ...
   return array[[myObjC count]];

Where the outer [] is the C++ operator [] call, and the inner [] is an 
Objective C method call.


-- 
William Edward Woody   -   woody@[EMAIL PROTECTED]
 In Motion        -   http://www.chaosinmotion.com

Freedom is the non-negotiable demand of human dignity; 
the birthright of every person‹-in every civilization.
            - National Security Strategy of the United States