Add to a readonly collection in a constructor?

Question

Is there a c# language construct that will allow me to add items to a readonly collection property in a constructor? I want to do something like this:

public cl         


        

Answer 1

To use the collection initializer syntax from you second code snippet your Node class must implement IEnumerable and have a public method with the signature

void Add(Node child)

Hence such a class cannot offer the immutability you desire. I think the best solution to your problem would be to do this

public class Node
{
  public readonly IEnumerable Children;

  public Node(IEnumerable children)
  {
    Children = children;
  }
}

or if you do not like the deferred execution of IEnumerable:

public class Node
{
  public readonly ReadOnlyCollection Children;

  public Node(IEnumerable children)
  {
    Children = new ReadOnlyCollection(children);
  }
}