Implicitly convert collection (HashSet) to IEnumerable<T>
.net, c#, casting, collections, linq
Solution
You can implicitly convert `HashSet<T>` to `IEnumerable<T>`, because HashSet, like ewvery other generic collection type, implements `IEnumerable<T>`.
However, for obvious reasons, you cannot convert `HashSet<U>` to `IEnumerable<T>`, unless `U` is convertible to `T` (in which case you can use an implicit covariant conversion).
Your `HashSet` is (but probably should not be) a collection of `Enumeration<T>`, not `T`.
Problem
I have a simple abstract enumeration class: ``` public abstract class Enumeration<T> { protected readonly T _value; private static readonly HashSet<Enumeration<T>> _values = new HastSet<Enumeration<T>>(); protected Enumeration(T value) { _value = value; _values.Add(this); } } ``` Now I would like to have a method that returns every element in the HashSet, but not the HashSet itself ( -> as an IEnumerable). But this doesn't work: ``` public static IEnumerable<T> GetValues() { return _values; } ``` because I cannot implicitly convert `HashSet` to `IEnumerable<T>`, of course. The only way I can think of is looping through the HashSet and yielding every element, but I wonder if there's a way to do this automatically, like when you implicitly cast a list to an `IEnumerable<T>`.