unmodifiablelist in .NET 4.0

Question

From what I can tell, .NET 4.0 still lacks readonly lists. Can anyone shed light on why the framework still lacks this functionality? Isn't this one of the commonest pieces of functionality for domain drive design?

One of the few advantages Java has over C# is this in the form of the Collections.unmodifiablelist(list) method, which it seems is long overdue in IList or List.

Answer 1

In 2.0 you can call AsReadOnly to get a read-only version of the list. Or wrap an existing IList in a ReadOnlyCollection object.

Answer 2

How about ReadOnlyCollection already within the framework?

Answer 3

You're looking for ReadOnlyCollection, which has been around since .NET2.

List<string> foo = new List<string>();
// ...
ReadOnlyCollection<string> bar = foo.AsReadOnly();

Answer 4

If the most common pattern of the list is to iterate through all elements, IEnumerable or IQueryable can effectively act as a read-only list as well.

Answer 5

What's wrong with System.Collections.ObjectModel.ReadOnlyCollection?