XML Literal select with multiple nodes

Question

Hi there
can anybody tell the correct syntax for the following XML Literal:
        Dim x = <Test>
                    <%= From item In items Select
                         <top><%= item.X %></top>
                         <left><%= item.Y %></left>
                    %>
                </Test>
Which should result in something like the following valid xml:
<Test>
  <top>1</top>
  <left>2</left>
  <top>4</top>
  <left>6</left>
</Test>
Thanks in advance.
Paul

Answer 1

Hi,
using a classic loop is a possibility, but there are also LINQ solutions, using an array or an iterator:
Dim items As New List(Of Point) From {
New Point(1, 2),
New Point(4, 6)}
' Array versions
Dim result As XElement = New XElement("Test", items.Select(
Function(item)
Return {
New XElement("Top", item.Y),
New XElement("Left", item.X)}
End Function))
Console.WriteLine("Array LINQ Syntax: " & result.ToString())
Dim result2 As XElement =
<Test>
<%= items.Select(Function(item)
Return {
<Top><%= item.Y %></Top>,
<Left><%= item.X %></Left>}
End Function) %>
</Test>
Console.WriteLine("Array VB Syntax: " & result2.ToString())
' Iterator versions requires VB2012 or later
Dim result3 As XElement = New XElement("Test",
items.Select(
Iterator Function(item)
Yield New XElement("Top", item.Y)
Yield New XElement("Left", item.X)
End Function))
Console.WriteLine("Iterator LINQ Syntax: " & result3.ToString())
Dim result4 As XElement =
<Test>
<%= items.Select(
Iterator Function(item)
Yield <Top><%= item.Y %></Top>
Yield <Left><%= item.X %></Left>
End Function)
%>
</Test>
Console.WriteLine("Iterator VB Syntax: " & result4.ToString())
I would consider the Visual Basic syntax (results 2 and 4) at last, as they only add overhead.
The iterator variants require Visual basic 2012 or later. They are lazy evaluated, which has no use here, but in more complex scenarios there can be some advantages.
Regards, Elmar