data structures - Multi-key dictionaries (of another kind) in C#?

Question

Building on this question, is there a simple solution for having a multi-key dictionary where either key individually can be used to identify the value?

ie.

MultikeyDictionary<TKey1, TKey2, TValue> foo;
foo.Add(key1, key2, value);
myValue = foo[key1];
// value == myValue
foo.Remove(key2);
myValue = foo[key1]; // invalid, Exception or null returned

Answer 1

This blog post seems to detail a rather decent implementation.

Multi-key generic dictionary class for C#

MultiKeyDictionary is a C# class that wraps and extends the Generic Dictionary object provided by Microsoft in .NET 2.0 and above. This allows a developer to create a generic dictionary of values and reference the value list through two keys instead of just the one provided by the Microsoft implementation of the Generic Dictionary<...>. You can see my article on CodeProject (here), however this code is more up-to-date and bug free.