.NET dictionary with two keys and one value

Question

Is there a dictionary available in .NET that could hold 2 keys and one value. Like

Dictionary(Of TKey, Of TKey, TValue)

I have

Answer 1

As a local solution I use the easy approach:

Imagine I have a collection of products identified by a string and a form with buttons for each one of the products.

When managing the state of the buttons I need to find buttons by string key. When handling the clicks I need to find product IDs by button instance.

Instead of maintaining two separate dictionaries I do the following:

public class SPurchaseOption
{
    public Button Button;
    public string ProductID;
    public string SomeOtherAssociatedData;
}

Dictionary purchaseOptions;

When the buttons are initialized I append two entries into the Dictionary i.e.

Key: ProductID, Value: "SPurchaseOption"
Key: Button,    Value: "SPurchaseOption"

For a more general approach and if you need a commonly used component you will have to build a wrap around two dictionaries i.e:

public class DoubleKeyedDictionary
{
    class SItem
    {
        public TKey1 key1;
        public TKey2 key2;
        public TValue value;
    }

    Dictionary dic1;
    Dictionary dic2;
}

this will give access to both the value and alternative key by any of the keys.