Re: [Bibdesk-develop] plugins built as 64 bit?

[Adam R. Maxwell]

On Sep 5, 2009, at 11:27 AM, Christiaan Hofman wrote:

On Sep 5, 2009, at 19:59, Adam R. Maxwell wrote:

On Sep 5, 2009, at 10:43 AM, Christiaan Hofman wrote:

And now I know why PDFKit doesn't work on 64 bits. They are really
messing up writing to ivars. Remember they use weird private classes

read/write to these ivars, because these private classes don't have
accessors.

to hide the ivars. This means they must be using runtime functions to

Is it really using runtime functions?  I've done this by

@class PublicClassIvars;

@interface PublicClass : NSObject
{
@private
  PublicClassIvars *_ivars;
}
@end

/// In the implementation of PublicClass, declare the ivars

@interface PublicClassIvars : NSObject
{
@public
  id        _representedObject;
  NSInteger _type;
}
@end

and you can access it in PublicClass by

NSInteger t = _ivars->_type;
id obj = _ivars->_representedObject;

Basically this is the Pimpl idiom, using an object instead of an
opaque pointer, and it's pretty easy unless you have object types
and need to manage memory.  It would be interesting to set a
breakpoint on the objc runtime functions and see if PDF Kit is
calling them.  If so, that's really the hard way of doing it; you
might as well use indexed ivars!

That sounds very dangerous, especially in view of Objective-C 2.0 and
64 bits. Moreover, the compiler complains very hard, and the docs say
not to use @defs in 64-bits. Remember they're making objects more and
more opaque. Anyway, PDFKit for sure does it the hard way by adding
all those private ivar wrapping objects.

#import <Foundation/Foundation.h>

@class PublicClassIvars;

@interface PublicClass : NSObject
{
@private
   PublicClassIvars *_ivars;
}
@end

@interface PublicClassIvars : NSObject
{
@public
   id        _representedObject;
   NSInteger _type;
}
@end

@implementation PublicClassIvars
@end

@implementation PublicClass

- (id)init
{
    self = [super init];
    if (self) {
        _ivars = [PublicClassIvars new];
        _ivars->_representedObject = [NSObject new];
        _ivars->_type = 1;
    }
    return self;
}

- (NSString *)description
{

}

@end

int main (int argc, char const *argv[])
{
    NSAutoreleasePool *pool = [NSAutoreleasePool new];

    PublicClass *x = [PublicClass new];
    NSLog(@"%@", [x description]);


    return 0;
}

No, this works fine in 64 bit (I use it in FileView); the important part is @public in the declaration of PublicClassIvars, which obviates the need for @defs since you already have access to _ivars from PublicClass. For true opaque objects, you'd use @dynamic, but then I think you have to use @property accessors...which would eliminate the private ivar object also. return [NSString stringWithFormat:@"%@:\n\trepresented object = %@ \n\ttype = %d", [super description], _ivars->_representedObject, _ivars->_type];

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