Sorting arrays with cyclic compares (infinite loop?)
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by Tiago
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Published on 2010-02-24T17:00:03Z
Indexed on
2010/03/30
15:03 UTC
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Hi,
I have some objects that have 3 sorting options: quality, quatity and a compare against the other object, sorted by that order.
- (NSComparisonResult) compare: (MyObject *) obj {
if (self.quality > obj.quality)
return NSOrderedAscending;
else if (self.quality < obj.quality)
return NSOrderedDescending;
if (self.quantity > obj.quantity)
return NSOrderedAscending;
else if (self.quantity < obj.quantity)
return NSOrderedDescending;
if ([self betterThan: obj])
return NSOrderedAscending;
if ([obj betterThan: self])
return NSOrderedDescending;
return NSOrderedSame;
}
My problem is that, the betterThan: method might cause a cyclic compare if the objects have the same quality and quantity, and I want to return any sort order in that case.
For example, A, B and C have the same quality/quantity, but
A betterThan: B => YES
B betterThan: C => YES
C betterThan: A => YES
Solutions? Thanks.
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