Question

I need the following (using string as the type here for brevity):

MyDictionary : IDictionary<string, List<string>>
{
    private readonly Dictionary<string, List<string>> _collection;
    ...
    // The collection cannot contain the key
    public void Add(string key, List<string> value)
    {
        _collection.Add(key, new List<string>(value.RemoveAll(p => p == key));
    }
}

So in use you might have:

string myName = "Superstringcheese";
List<string> myFriends = new List<string> {"John", "Jane", "Jerry"};

string yourName = "Someone";
List<string> yourFriends = new List<string> {"John", "Bill", "Ted"};

var myDic = new MyDictionary();

// It's okay that each of us (each key) has some friends that are the same. It's not okay for me to have myself as a friend. The add method would check if the key is contained by the value collection and remove it if necessary.
myDic.Add(myName, myFriends);
myDic.Add(yourName, yourFriends);

Before I go reinventing any wheels, is there a native collection type that does this, or does anyone know of a popular implementation?

Answer 1

Well, I can help with this bit:

Is there a native collection type that does this?

No.