Re[2]: [NSDecimalNumber numberWithDouble:x]

[Manuel Guesdon]

On Mon, 12 Jan 2004 13:05:27 +0100 David Ayers <address@hidden> wrote:

 >| Manuel Guesdon wrote:
 >| > On 10 Jan 2004 21:00:44 -0700 Adam Fedor <address@hidden> wrote:
 >| > 
 >| >  >| On Sat, 2004-01-10 at 07:12, Manuel Guesdon wrote:
 >| >  >| > Hi,
 >| >  >| > 
 >| >  >| > [NSDecimalNumber numberWithDouble:x] retunrs a NSDoubleNumber, not 
 >a NSDecimalNumber.
 >| >  >| > Is it correct ? 
 >| >  >| > If yes what is the interest of NSDecimalNumber -initWithDouble: ?
 >| >  >| > Won't it be better to have a NSDecimalNumber -numberWithDouble: ?
 >| >  >| > 
 >| >  >| > And same with for all numberWithXX: ?
 >| >  >| > 
 >| >  >| 
 >| >  >| Yes, NSDecimalNumber probably needs to override all the number methods
 >| >  >| (unless we wanted to put a special check in NSNumber for allocation 
 >from
 >| >  >| subclasses).
 >| > 
 >| > Have you (or someone) a preference for the method to use ? override or 
 >check in numberWithXX:, like the following
 >| ?
 >| > 
 >| > + (NSNumber*) numberWithDouble: (double)value
 >| > {
 >| >   NSNumber      *theObj;
 >| >         if ([self isKindOfClass:decimalNumberClass])
 >| >                 theObj=[[self alloc]initWithDouble: value];
 >| >         else
 >| >         {
 >| >           theObj= (NSNumber*)NSAllocateObject(doubleNumberClass, 0,
 >| >                     NSDefaultMallocZone());
 >| >                   theObj = [theObj initWithBytes: &value objCType: NULL];
 >| >         }
 >| >   return AUTORELEASE(theObj);
 >| > }
 >| > 
 >| > Overriding avoid additional code in NSNumber and avoid slowing it.
 >| > 
 >| >
 >| Hello,
 >| 
 >| Acutally I agree with Adam.  NSNumber should allow *any* custom 
 >| subclasses "to do the right thing".  These aren't primiative methods. 
 >| So therefor these look like bugs in the NSNumber implementation to me. 
 >| I think all these numberWith*: methods should test:
 >| if (self == [NSNumber class] || self == [applicableConcreteClass class])
 >| (or rather the cached versions) before executing their current 
 >| implementations using the NSAllocateObject function.  Otherwise it 
 >| should probaly just call [[self alloc] initWith*:] as you have done.

OK. Should we test against NSNumber class only or also against NSDoubleNumber, 
NSShortNumber, ... for cases like:
[NSDoubleNumber numberWithDouble:xx] ? As far as I remember, NSDoubleNumber,... 
are no more declared as public. So I'm
not sure this is a real problem....

BTW, as I've got another problem, what is the correct way to test if a NSNumber 
is a NSDoubleNumber or a NSFloatNumber,...
before recent changes, we were able to use  isKindOfClass:[NSDoubleNumber 
class] ? It's interesting to know the kind of
data and use appropriate methods to keep precision

Thx.


Manuel

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