Can I Create a Dictionary of Generic Types?

Question

I\'d like to create a Dictionary object, with string Keys, holding values which are of a generic type. I imagine that it would look something like this:

Dict         


        

Answer 1

I came to a type safe implementation using ConditionalWeakTable.

public class FieldByType
{
    static class Storage
        where T : class
    {
        static readonly ConditionalWeakTable table = new ConditionalWeakTable();

        public static T GetValue(FieldByType fieldByType)
        {
            table.TryGetValue(fieldByType, out var result);
            return result;
        }

        public static void SetValue(FieldByType fieldByType, T value)
        {
            table.Remove(fieldByType);
            table.Add(fieldByType, value);
        }
    }

    public T GetValue()
        where T : class
    {
        return Storage.GetValue(this);
    }

    public void SetValue(T value)
        where T : class
    {
        Storage.SetValue(this, value);
    }
}

It can be used like this:

/// 

/// This class can be used when cloning multiple related objects to store cloned/original object relationship.
/// 
public class CloningContext
{
    readonly FieldByType dictionaries = new FieldByType();

    public void RegisterClone(T original, T clone)
    {
        var dictionary = dictionaries.GetValue>();
        if (dictionary == null)
        {
            dictionary = new Dictionary();
            dictionaries.SetValue(dictionary);
        }
        dictionary[original] = clone;
    }

    public bool TryGetClone(T original, out T clone)
    {
        var dictionary = dictionaries.GetValue>();
        return dictionary.TryGetValue(original, out clone);
    }
}