Elegant way to create a nested Dictionary in C#

Question

I realized that I didn\'t give enough information for most people to read my mind and understand all my needs, so I changed this somewhat from the original.

Answer 1

Define your own custom generic NestedDictionary class

public class NestedDictionary<K1, K2, V>: 
     Dictionary<K1, Dictionary<K2, V>> {}

then in your code you write

NestedDictionary<int, int, string> dict = 
       new NestedDictionary<int, int, string> ();

if you use the int, int, string one a lot, define a custom class for that too..

   public class NestedIntStringDictionary: 
        NestedDictionary<int, int, string> {}

and then write:

  NestedIntStringDictionary dict = 
          new NestedIntStringDictionary();

EDIT: To add capability to construct specific instance from provided List of items:

   public class NestedIntStringDictionary: 
        NestedDictionary<int, int, string> 
   {
        public NestedIntStringDictionary(IEnumerable<> items)
        {
            foreach(Thing t in items)
            {
                Dictionary<int, string> innrDict = 
                       ContainsKey(t.Foo)? this[t.Foo]: 
                           new Dictionary<int, string> (); 
                if (innrDict.ContainsKey(t.Bar))
                   throw new ArgumentException(
                        string.Format(
                          "key value: {0} is already in dictionary", t.Bar));
                else innrDict.Add(t.Bar, t.Baz);
            }
        }
   }

and then write:

  NestedIntStringDictionary dict = 
       new NestedIntStringDictionary(GetThings());

Answer 2

You may be able to use a KeyedCollection where you define:

class ThingCollection
    : KeyedCollection<Dictionary<int,int>,Employee>
{
    ...
}