Ex. 11.2: the shortest comparison implementation ever!

[Jemcik]

Fraction+Comparison.h

Code: (Objective-C)

#import "Fraction.h"

@interface Fraction (Comparison)

-(BOOL) isEqualTo: (Fraction *) f;
-(int) compare: (Fraction *) f;

@end

Fraction+Comparison.m

Code: (Objective-C)

#import "Fraction+Comparison.h"

@implementation Fraction (Comparison)

-(BOOL) isEqualTo: (Fraction *) f
{
    return ![self compare:f] ? TRUE : FALSE;
}

-(int) compare: (Fraction *) f
{
    int a = num * f.den; 
    int b = f.num * den;
    return a == b ? 0 : a > b ? 1 : -1;
}

@end

Pay attention that receiver and argument remains unchanged in both methods,
and everything is done in -(int) compare: (Fraction *) f actually