Read-Only List in C#

You can expose a List<T> as a ReadOnlyCollection<T> by using the AsReadOnly() method

C# 6.0 and later (using Expression Bodied Properties)

class Foo { 

  private List<int> myList;

  public ReadOnlyCollection<int> ReadOnlyList => myList.AsReadOnly();

}

C# 5.0 and earlier

class Foo {

  private List<int> myList;

  public ReadOnlyCollection<int> ReadOnlyList {
     get {
         return myList.AsReadOnly();
     }
  }
}