Generic collection with IEqualityComparer in constructor

Question

Is there any collection in framework like that?

public class DesiredCollection<T>
{
    public DesiredCollection(IEqualityComparer<T> comparer) 
    {
    }
}

Requirements:

• generic collection;
• IEqualityComparer or lambda-expression to determine equality;
• no need to define key type;
• getting item by key;
• getting all items as IEnumerable.

Answer 1

Various collections take IEqualityComparer<T> in their constructors (usually as one overload out of several). In particular, Dictionary<TKey, TValue> and HashSet<T> fall into this category. They use the equality comparer to check for the existence of keys / elements.

However, you haven't really expressed anything other than the need for a constructor taking an equality comparer. Presumably you'll need more than that... what are you trying to do?