How should I use properties when dealing with read-only List members

Question

When I want to make a value type read-only outside of my class I do this:

public class myClassInt
{
    private int m_i;
    public int i {
        get { ret         


        

Answer 1

You can expose it AsReadOnly. That is, return a read-only IList wrapper. For example ...

public ReadOnlyCollection List
{
    get { return _lst.AsReadOnly(); }
}

Just returning an IEnumerable is not sufficient. For example ...

void Main()
{
    var el = new ExposeList();
    var lst = el.ListEnumerator;
    var oops = (IList)lst;
    oops.Add( 4 );  // mutates list

    var rol = el.ReadOnly;
    var oops2 = (IList)rol;

    oops2.Add( 5 );  // raises exception
}

class ExposeList
{
  private List _lst = new List() { 1, 2, 3 };

  public IEnumerable ListEnumerator
  {
     get { return _lst; }
  }

  public ReadOnlyCollection ReadOnly
  {
     get { return _lst.AsReadOnly(); }
  }
}

Steve's answer also has a clever way to avoid the cast.