Question

I wish to use HashSet<T> as the key to a Dictionary:

Dictionary<HashSet<T>, TValue> myDictionary = new Dictionary<HashSet<T>, TValue>();

I want to look up values from the dictionary such that two different instances of HashSet<T> that contain the same items will return the same value.

HashSet<T>‘s implementations of Equals() and GetHashCode() don’t seem to do this (I think they’re just the defaults). I can override Equals() to use SetEquals() but what about GetHashCode()? I feel like I am missing something here…

Answer 1

You could use the set comparer provided by HashSet<T>:

var myDictionary = new Dictionary<HashSet<T>, TValue>(HashSet<T>.CreateSetComparer());