Effectively disable Sort() within a CompareTo() override?

Question

The CompareTo() method for my class is dynamic, and can range from a simple comparison to comparisons on a number of columns. This is all determined at run time, and it works great.

But in some cases, I want any attempt to sort a collection of my objects using the default comparison to just do nothing.

Having CompareTo() just return a 0 for any comparison, to my surprise, doesn't work. The list gets rearranged in some odd, seemingly-random order.

Is there a way to do this in the CompareTo() method implementation? I'd rather not handle this up at the collection level by having to override Sort().

Answer 1

I haven´t proved it, but as a suggestion, what if you try to return always 1, or always -1?

Answer 2

You have to override Sort(). The default implementation of Sort() offers no guarantees about how it will use CompareTo() to arrive at a sorted collection, so there isn't any way to use it to make Sort() do the right thing.

Answer 3

That's because QuickSort is not a stable sort. I don't see a good option to fix this in the CompareTo method unless you can somehow obtain the index of the element.