Namespace prefix and VB XML axis properties

Question

I just want to verify a conceptual issue.

This code is given in a tutorial at http://msdn.microsoft.com/en-us/library/bb943911.aspx

    Public Function ParagraphText(ByVal e As XElement) As String
        Dim w = e.Name.Namespace
        Return (e.<w:r>.<w:t>).StringConcatenate(Function(element) CStr(element))
    End Function

But you cannot use namespace prefixes like this in VB axis properties can you? This example only happens to work because the code file

Imports <xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">

That is, the fortuitous choice of "w" as the temp namespace variable collides with the imported global namespace prefix, and that's the only reason the "e.<w:r>..." syntax is valid?

I'm interested because I'd like to write a method that can access child elements of an XElement using sytnax that ensures they are in the namespace of the parent (not directly available in the called context).

I can do it with explicit LINQ methods, but not axis properties (not sure if terminology is correct. The distinction I'm trying to make is clear in the code below between the commented and uncommented regions). Here is my attempt:

    Public Sub InitFromXElement(xel As XElement)
        Dim w As XNamespace = xel.Name.Namespace

        Debug.Print("Namespace of xel=" & w.ToString())

        'Me.Name = xel.<w:Name>(0).Value
        'Me.Field = xel.<w:Field>(0).Value
        'Me.Description = xel.<w:Description>(0).Value
        'Me.Unit = xel.<w:Unit>(0).Value
        Me.Name = xel.Element(w + "Name").Value
        Me.Field = xel.Element(w + "Field").Value
        Me.Description = xel.Element(w + "Description").Value
        Me.Unit = xel.Element(w + "Unit").Value

    End Sub

Answer 1

I agree with you, prefixes used in VB.NET axis properties need to be defined globally with "Imports" directives as the VB.NET compiler translates the code into normal axis methods calls at compile time.

Thus if you want to use XNamespace objects you need to use the axis methods like e.g. foo.Elements(w + "Name") or foo.Descendants(w + "Name").

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