Why does XElement not behave like a reference type?

Question

I noticed that XElement is a class, so I tried something like:

var doc = new XDocument(
    new XDeclaration("1.0", "utf8", "yes"),
    new XElement("Root")
    );
var root = doc.Root;
var com = new XElement("Component", new XAttribute("name", "arm"));
root.Add(com);
root.Add(com);
root.Add(com);
com.Add(new XAttribute("type", 1));

Console.WriteLine(doc);

but the output is:

<Root>
  <Component name="arm" type="1" />
  <Component name="arm" />
  <Component name="arm" />
</Root>

I also tried SetAttributeValue(), and got the same result.

Why is the type attribute only attached to the first component?

Answer 1

My original answer stands (essentially "by design") and here is a reason why...

From MS Documentation (and following the relevant links) you will find that

• XElement inherits XContainer inherits XNode
• XContainer has method Add() and properties FirstNode and LastNode
• XNode has properties NextNode and PreviousNode

If Add() blindly added references to the same object without creating copies where necessary to avoid multiple-referencing, how could circular references be avoided? In your example above, FirstNode and FirstNode.NextNode would reference the same object.