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Unexpected duplicates in Set
f#

Hello,
I've just spent a few hours trying to solve an awkward problem and I all my efforts have failed miserably.
Basically here's the issue: I've got a custom type containing several fields, among which there's a string.
I've implemented IComparable.CompareTo this way:

interface IComparable with
member x.CompareTo z =
if z <> null then
match z with
| :? MyType -> x.MyString.CompareTo((z :?> MyType).MyString)
| _ -> failwith "Invalid type"
else
failwith "Can't compare against a null object"

I've also implemented GetHashCode this way:

override x.GetHashCode() = _MyString.GetHashCode()

Yet when I try to create a set of my custom type it will not be able to recognize duplicate items adequately.
Any clues on what I'm doing wrong?

Best Regards

.

In the example you only compare the strings, so your duplicate values may differ in the other fields. Or maybe it's some Unicode issue because you use String.CompareTo instead of String.CompareOrdinal. If you could come up with some minimal but complete example demonstrating the problem, it would be easier to make a specific diagnosis.

By on 12/19/2008 12:15 AM ()

Thanks but I've just solved it, in my data set there were items with the same string and different casing and I was unaware of that. By the way the comparison only on the string was on purpose ;)

Best Regards

By on 12/19/2008 2:12 AM ()

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