Can .NET 4 ISet<> HashSet<> replace NHibernate Iesi.Collections ISet , HashSet?

Question

Can .NET 4 ISet<> HashSet<> replace NHibernate Iesi.Collections ISet , HashSet ? I am using Castle proxy, and NHibernate 3.0 .

Answer 1

No, not as of this reply.

The NHibernate engine uses the Iesi.Collections.ISet interface on internal collection classes which are used as wrappers around collections in your classes which NHibernate persists. There is no direct conversion to System.Collections.Generic.ISet<T>.

Update: NHibernate 4 now uses HashSet<T> from the BCL internally, and HashedSet<T> has been removed from the Iesi.Collections dependency. The approach to use System.Collections.Generic.ISet<T> is now available.

Answer 2

Yes. There are two approaches:

1. Declare your collection as ICollection<T> and initialize it as HashSet<T>. See this article. I model collections as private members and expose IEnumerable<T> so this works well, but the downside is that you can't expose ISet<T>.
2. Use Jose Romaniello's Set4Net4 NuGet package. See this article and the source code.

Answer 3

Yes, with Nhibernate 4, using System.Collections.Generic.ISet<> is now the way to go.