Other way around. The copy happens when you *set* the property.
So ray.path = OriginalPathPointerYouStartedWith;
will copy OriginalPathPointerYouStartedWith and then set ray's member
variable to that copy. However when you READ the property, it just
returns what's in the member variable over and over again.
If you wanted it to return a copy you could if you wish write your own
accessor
-(NSBezierPath*)path
{
return( [ [ path copy ] autorelease ] );
}
which would copy it when it's accessed and give the accessor its own
one to play with. So it would be copied when you set it, and then
copied when you returned it. I'm not totally sure how much I like
that, it feels a little semantically wrong to me but in the context of
your class that might make sense. Were I really going to do that I may
not use a property at all and might have a method which is called
(NSBezierPath*)copyPath
which explicitly returns a copy of the path because that's clear.
On 30-Sep-2009, at 9:02 PM, Colin Howarth wrote:
Hi,
I have a class
@interface Ray : NSObject {
...
NSBezierPath *path;
...
}
@property (copy) NSBezierPath *path;
@end
an instance of which is accessed in another class:
- (void)drawRect:(NSRect)rect
{
NSBezierPath *temporaryPathPointerWhichIsSupposedToBeDifferent;
...
temporaryPathPointerWhichIsSupposedToBeDifferent = [ray.path];
[temporaryPathPointerWhichIsSupposedToBeDifferent
transformUsingAffineTransform: aVeryLongDescriptiveTransformName];
[temporaryPathPointerWhichIsSupposedToBeDifferent stroke];
...
}
I thought the (copy) attribute would mean that
temporaryPathPointerWhichIsSupposedToBeDifferent would be, well, a
copy of the original path instance (which conforms to the NSCopying
protocol). Of course, the compiler doesn't care what *I* think
should happen, and applies the transform to path (which is identical
to temporaryPathPointerWhichIsSupposedToBeDifferent).
It works if I do:
temporaryPathPointerWhichIsSupposedToBeDifferent = [ray.path copy];
instead.
Why isn't it doing what I think it should do though?
Thanks,
colin
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