Thoughts on how prototypical inheritance might be done in Objective-C. Notice that the Étoilé runtime (the predecessor to the GNUstep runtime) actually supports such things anyway.

gistfile1.m

#import <Foundation/Foundation.h>
#import <objc/runtime.h>

@interface A : NSObject
- (void)createPrivateSubclass;
@end

int main(int argc, char *argv[])
{
  @autoreleasepool
	{
		A *a = [A new];
		NSLog(@"Before: %@", [a class]);
		[a createPrivateSubclass];
		NSLog(@"After: %@", [a class]);
	}
}

@implementation A

- (void)createPrivateSubclass
{
	NSString *className = [[NSUUID UUID] UUIDString];
	Class newClass = objc_allocateClassPair([self class], [className UTF8String], 0);
	object_setClass(self, newClass);
}

@end

I think this is an interesting step towards prototypal inheritance, definitely; actual cloning is of course more complex as methods have to be resolved with respect to the parent. Interesting.