Question

I have a problem with a List of objects …

This List contains objects which themselves contain objects, and so on … (all objects are of the same type)

My objects looks like that :

  public class MyObject (...)
  {
    ...
    public MyObject[] Object;
    ...
  }

I’d like to change some variables of these objects (according to certain parameters), and to do that I think using LINQ.

My problem is that I do not really know how to do something that will pass through ALL my recursive List, regardless of their level.

I hope I was as clear as possible.

Thank you in advance for your help.

Answer 1

You can write a simple recursive method to do what you want easily enough:

public static void Touch(MyObject obj, string otherParameter)
{
    obj.Value = otherParameter;
    foreach (var child in obj.Object)
    {
        Touch(child, otherParameter);
    }
}

If you really, really want a more LINQ-esque method, or you do this often enough to need a more generic approach, you could use something like this:

public static IEnumerable<T> FlattenTree<T>(IEnumerable<T> source, Func<T, IEnumerable<T>> selector)
{
    //you could change this to a Queue or any other data structure 
    //to change the type of traversal from depth first to breath first or whatever
    var stack = new Stack<T>(); 
    while (stack.Any())
    {
        T next = stack.Pop();
        yield return next;
        foreach (T child in selector(next))
            stack.Push(child);
    }
}

You could then use it like:

MyObject root = new MyObject();

var allNodes = FlattenTree(new[] { root }, node => node.Object);
foreach (var node in allNodes)
{
    node.Value = "value";
}