Which interface should I expose a List<T> via?

Question

In a response to this question runefs suggested that "unless you have a very specific reason for using IList you should considere IEnumerable". Which do you use and why?

Answer 1

IEnumberable<T> is read-only, you have to reconstruct the collection to make changes to it. On the other hand, IList<T> is read-write. So if you expect a lot of changes to the collection, expose IList<T> but if it's safe to assume that you won't modify it, go with IEnumerable<T>.