Embed Code and Avoid Underscores in Your Multiline Strings

Embed Code and Avoid Underscores in Your Multiline Strings

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One of the things I most dearly missed from FoxPro when I moved to VB.NET was the ability to easily dump a bunch of text (multi-line string literals) into the editor easily and embed code (text-merge). FoxPro has a keyword TEXT...ENDTEXT for this and I used to use it all the time. In VB it gets pretty darn ugly with any large amount of text because you have to concatenate string literals with your code and use underscores for readability.

  Dim oldWay = "this is a string" & vbCrLf & _

               "with formatting" & vbCrLf & _

               "and stuff" & vbCrLf & _

               "look ma, underscores" & vbCrLf & _

               "         tabs too"

 

  MsgBox(oldWay)

Not any more. With Visual Basic 9's built in XML literals support we can now easily write a bunch of text directly into the editor:

         Dim newWay = <string>

this is a string

with formatting

and stuff

look ma, no underscores!!!

            tabs too

                </string>

 

        MsgBox(newWay.Value)

The text formatting is preserved as well. All you have to do is get the .Value of the XElement, which is the string literal. As you can see this is much cleaner than what we're used to. And if you still like to see your string literals in the default reddish color, you can easily change the color settings for VB XML literals in Tools --> Options --> Environment --> Fonts and Colors, then select "VB XML Text" and set the custom color to RGB(163,21,21). Here's another example, some SQL query text (now with the reddish color): 

        Dim query = <query>

SELECT Customers.*, Orders.OrderDate

FROM Customers

    INNER JOIN Orders ON Orders.CustomerID = Customers.CustomerID

WHERE Customers.CustomerID = @CustomerID

                    </query>

 

        Dim cmd As New SqlCommand(query.Value)

        cmd.Parameters.AddWithValue("@CustomerID", id)

Now here's where it gets fun. You can also embed expressions into these literals with the <%= syntax. This means you can do any kind of text merging much cleaner than ugly concatenation of strings with code or use of String.Format especially as the size of the text increases. Here's some simple examples:

        Dim simple = <string>

This is a simple text merge example:

Hello, <%= Environment.UserName %>

                     </string>

 

        MsgBox(simple.Value)

 

 

        Dim controls = <string>

There are the following controls on this form:

<%= From item In Me.Controls Select item.ToString & vbCrLf %></string>

 

        MsgBox(controls.Value)

Calvin has some good examples here and here on how to generate scripts dynamically, but here's one that uses a simple code generation pattern. 

Private Sub CreateClass()

        Dim CustomerSchema As XDocument = XDocument.Load(CurDir() & "\customer.xsd")

 

        Dim fields = From field In CustomerSchema...<xs:element> _

                     Where field.@type IsNot Nothing _

                     Select Name = field.@name, Type = field.@type

 

 

        Dim customer = <customer>

Public Class Customer

    <%= From field In fields Select <f>    

        Private m_<%= field.Name %> As <%= GetVBPropType(field.Type) %></f>.Value %>

 

        <%= From field In fields Select <p>    

        Public Property <%= field.Name %> As <%= GetVBPropType(field.Type) %>

            Get

                Return m_<%= field.Name %> 

            End Get

            Set(ByVal value As <%= GetVBPropType(field.Type) %>)

                m_<%= field.Name %>  = value

            End Set

        End Property</p>.Value %>                       

End Class</customer>

 

        My.Computer.FileSystem.WriteAllText("Customer.vb", customer.Value, _

False, System.Text.Encoding.ASCII)

 

    End Sub

 

    Private Function GetVBPropType(ByVal xmlType As String) As String

        Select Case xmlType

            Case "xs:string"

                Return "String"

            Case "xs:int"

                Return "Integer"

            Case "xs:decimal"

                Return "Decimal"

            Case "xs:boolean"

                Return "Boolean"

            Case "xs:dateTime", "xs:date"

                Return "Date"

            Case Else

                Return "'TODO: Define Type"

        End Select

    End Function

I hope this gives you some good ideas on what you can do with XML Literals. You literally (pun intended ;-)) don't have to use them to produce XML, you can use them to produce any text-based output.

Enjoy,
-B

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  • I have rug burn on my chin because of this post!

    I simply can NOT wait for the release, this is gonna be so awesome.

  • Josh,

    LOL! You can give it a try right now (Beta 2) if you have an extra machine or Virtual Machine laying around: http://msdn2.microsoft.com/en-us/vstudio/aa700831.aspx

    And congrats on starting your blog! ;-)

  • I'd love to give it a try but I dont an extra machine laying around.  Ok, well I do, but it is an antique unworthy of any version of VS!!

    Thanks :)

    I might ask around at work and see if there is a "playground" machine I can have for a while.

  • Beth, I'm stealing, er, uh, borrowing some of these examples for my "What's new in VB9" talk at DevConnections Las Vegas. Your name will be mentioned prominently.

  • Hi Billy!,

    For you, anything! ;-) Ping me directly if you need any more demos, decks, etc. I'll be speaking at Silicon Valley code-camp this weekend and then QCon in SF Nov 9th so I've pulling demos together this week.

    -B

  • Ένα από τα νέα χαρακτηριστικά της VB.NET είναι η υποστήριξη XML Literals. Πρόκειται για τη δυνατότητα

  • A couple quick tips here when using XML literals in your Visual Basic programs. #1: I've started using

  • Hi Beth,

    XML literals are one of my favourite new features in VB9, really looking forward to using this in a real product.

    I'm not sure I like it for multiline strings though, because of the break in indentation. It's still a pretty cool idea though. :)

  • We just released a new set of How-Do-I videos in our LINQ series on LINQ to XML in Visual Basic. These

  • We just released a new set of How-Do-I videos in our LINQ series on LINQ to XML in Visual Basic. These

  • I've mentioned before that you can use XML literals in VB 9 to do text merging so I figured it should

  • I&#39;ve mentioned before that you can use XML literals in VB 9 to do text merging so I figured it should

  • A while back I showed a very simple way you could use XML Literals to generate code. In my previous life

  • Hi

    Can you please let us know if VB can read a text file of around 90 MB file size and process relevant data out of it.

    Thanks

    Nishtha

  • So why did it take Microsoft 16 years to implement a form of multi-line strings? (Working from the original May 1991 release date for VB 1.0, Comdex/Windows World trade show in Atlanta, Georgia) The original bourne shell released with Unix Version 7 (in 1977) had here-documents.

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