泛型类继承自Dictionary with Collection

Question

I have this custom Dictionary with Collection definition:

class CollectionDictionary<K, C, V> : Dictionary<K, C> where C : ICollection<V>, new()

and using it like this (eg):

CollectionDictionary<Guid, HashSet<int>, int> sample;

but for me this double int seems awkward, is there a possibility to bypass this and only write:

CollectionDictionary<Guid, HashSet<int>> sample;

so that the compiler knows that V could only be an int?

EDIT:

I need the class to abstract this method

public void Add(K key, V value)
{
    if (!this.ContainsKey(key))
    {
        base.Add(key, new C());
    }
    this[key].Add(value);
}

Answer 1

You can do this

class CollectionDictionary<K, C> : Dictionary<K, ICollection<C>>

It removes the constraint you had that makes the ICollection have an empty constructor.

In order to be able to create new collections you could ask for a delegate that does that. But in your case I think your original solution would produce less boilerplate code.

// ctor
public CollectionDictionary(Func<ICollection<C>> collectionCreator)

// Create
base.Add(key, _collectionCreator());

// Init
new CollectionDictionary<Guid, int>(() => new HashSet<int>());