Question

Is that possible to get current Enumerator (…or iterator? Don’t know which tern is the correct one) in a LINQ query ?

For example, I try to create a XML output (via LINQ to XML) of all currently loaded assemblies.

Dim xmldoc As XDocument = New XDocument(
        New XElement("Types",
        Assembly.GetExecutingAssembly().GetReferencedAssemblies() _
                .Select(Function(name) Assembly.Load(name)) _
                .SelectMany(Function(assembly) assembly.GetTypes()) _
                .Select(Function(type) New XElement("Type", type.FullName))))

Tho output looks like this.

<Types>
  <Type>System.Object</Type>
  <Type>FXAssembly</Type>
  <Type>ThisAssembly</Type>
  <Type>AssemblyRef</Type>
  <Type>System.Runtime.Serialization.ISerializable</Type>
  <Type>System.Runtime.InteropServices._Exception</Type>
  .....
</Types>

is it possible to somehow get current “index” (counter?) from LINQ’s Selects? I would like to use it in XML

<Types>
  <Type ID="1">System.Object</Type>
  <Type ID="2">FXAssembly</Type>
  <Type ID="3">ThisAssembly</Type>
  <Type ID="4">AssemblyRef</Type>
  <Type ID="or-some-other-unique-id-#5">System.Runtime.Serialization.ISerializable</Type>
      .....
</Types>

Answer 1

Yup – you just need to use the overload of Select which takes a Func<TSource, int, TResult>. So in C# it would be something like:

XDocument doc = new XDocument(new XElement("Types",
    Assembly.GetExecutingAssembly().GetReferencedAssemblies()
        .Select(name => Assembly.Load(name))
        .SelectMany(assembly => assembly.GetTypes())
        .Select((type, index) => new XElement("Type",
                                              new XAttribute("ID", index + 1), 
                                              type.FullName))));

Sorry it’s not in VB, but it’s more likely to work this way – hopefully you can work out the translation 🙂