Hi, I just stumbled across a bug in NSNumber that I can't fix as I don't understand the NSNumber code. The problem is easy to see, though:
#import <Foundation/Foundation.h>
int main(int argc, char *argv[]) {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSNumber *n = [NSNumber numberWithInt:2];
NSNumber *nan = [NSDecimalNumber notANumber];
NSLog(@"%@ (class:%@ double:%g) == %@ -> %s",
n, NSStringFromClass([n class]), [n doubleValue],
nan, [n isEqualToNumber:nan] ? "YES" : "NO");
[pool release];
return 0;
}
On FreeBSD-8.2rc3 (amd64) this produces the following output:
2011-02-17 16:02:15.316 NumberTest[59574] 2 (class:NSIntNumber double:2) == NaN
-> YES
Which is clearly wrong.
I came across this issue via NSNumberFormatter, which instead of formatting any
integer numbers always printed NaN. In my project I tried to debug into the
issue and found this:
769 if ([anObject isEqual: [NSDecimalNumber notANumber]])
(gdb) s
-[NSNumber isEqual:] (self=0x803e8d1d0, _cmd=0x801410980, anObject=0x805e625c0)
at NSNumber.m:376
376 if ([anObject isKindOfClass: NSNumberClass])
(gdb) n
378 return [self isEqualToNumber: anObject];
(gdb) po anObject
NaN
(gdb) po [anObject class]
NSDecimalNumber
(gdb) s
-[NSNumber isEqualToNumber:] (self=0x803e8d1d0, _cmd=0x80140d300,
aNumber=0x805e625c0) at NSNumber.m:371
371 return ([self compare: aNumber] == NSOrderedSame) ? YES : NO;
(gdb) s
-[NSSignedIntegerNumber compare:] (self=0x803e8d1d0, _cmd=0x80140d2e0,
aNumber=0x805e625c0) at NSNumber.m:107
107 if (aNumber == self)
[…]
(gdb) n
165 double value = [self doubleValue];
(gdb) p other
$3 = nan(0x8000000000000)
(gdb) p value
$4 = 6.9533556002420585e-310
As you can see above, asking an NSIntNumber instance for its doubleValue works
properly, however, it fails at NSNumber.m:165. I don't know the reason, but I
also don't understand the implications of the macros used. Can somebody
elaborate? Please note that I'm on a 64-bit (amd64) system.
Thanks,
Marcus
--
Marcus Mueller . . . crack-admin/coder ;-)
Mulle kybernetiK . http://www.mulle-kybernetik.com
Current projects: http://www.mulle-kybernetik.com/znek/
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