Theocacao Comment for "Lazy Loading of KVO Observed Properties"

Comment on "Lazy Loading of KVO Observed Properties"
by Scott Stevenson — Jun 16

I don't know KVO, but remember that that static bool is static across instances as well

You're right, but it doesn't matter if all of this is being done in a single thread since only one getter is ever being called at a time. The example is simplistic by design. Here's an example for what you suggest (the setter should be the same as above):

@interface MyClass : NSObject
{
  NSImage myImage;
  BOOL myImageIsBeingSet;
}
@end

@implementation class

- (id)init
{
  if ( self = [super init] )
  {
    myImageIsBeingSet = NO;    
  }
  return self;
}

- (NSImage*)myImage
{
  if ( myImage == nil && myImageIsBeingSet == NO )
  {
    myImageIsBeingSet = YES;
    [self setMyImage:[self fetchImageFromDisk]];
    myImageIsBeingSet = NO;
  }  
  return myImage;
}
@end

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