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Asked: 2026-06-05T02:33:52+00:00

I’m creating an Activity Library in Visual Studio 11 Beta (although I’ve repeated all

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I’m creating an Activity Library in Visual Studio 11 Beta (although I’ve repeated all my steps in VS2010 with the same result), targeting the .NET 4.0 framework.

As I started entering arguments via the Workflow Designer, I noticed the “Enter a VB Expression” message in the Default Value box. I’m not sure how to change the language context from VB to C#.

To create the project, I followed these steps:

  1. Go to File> New and select Project…

  2. In the Installed> Templates section of the New Project dialog window, select Visual C#> Workflow> Activity Library

  3. Name the project, as usual, and click OK

And that’s basically it. I noticed then that the default Activity1.xaml file was expecting VB in the default values fields. I deleted it and then followed these steps to create a new Activity:

  1. Right-click on the project and select Add> New Item…

  2. In the Add New Item dialog window, navigate to Installed> Visual C# Items> Workflow> Activity

  3. Name the Activity and click OK

It was the same result, the Default Value fields are expecting a VB expression.

When I look at the XAML code, I can clearly see the Microsoft.VisualBasic.Activities namespace listed and a VisualBasic.Settings element, but I’m not sure what to do to change it; everytime I try, I just end up screwing things up. Here’s the XAML code being generated:

<Activity mc:Ignorable="sads sap" x:Class="THINKImport.CustomerAddOrderAdd"
 xmlns="http://schemas.microsoft.com/netfx/2009/xaml/activities"
 xmlns:local="clr-namespace:THINKImport.THINKWebReference"
 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
 xmlns:mva="clr-namespace:Microsoft.VisualBasic.Activities;assembly=System.Activities"
 xmlns:s="clr-namespace:System;assembly=System.Core"
 xmlns:s1="clr-namespace:System;assembly=System"
 xmlns:s2="clr-namespace:System;assembly=System.ServiceModel"
 xmlns:s3="clr-namespace:System;assembly=mscorlib"
 xmlns:sads="http://schemas.microsoft.com/netfx/2010/xaml/activities/debugger"
 xmlns:sap="http://schemas.microsoft.com/netfx/2009/xaml/activities/presentation"
 xmlns:t="clr-namespace:THINKImport"
 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<x:Members>
    <x:Property Name="user_login_data" Type="InArgument(local:user_login_data)" />
    <!--Removed the other properties for brevity-->
  </x:Members>
  <sap:VirtualizedContainerService.HintSize>440,440</sap:VirtualizedContainerService.HintSize>
  <mva:VisualBasic.Settings>Assembly references and imported namespaces for internal implementation</mva:VisualBasic.Settings>
</Activity>
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1 Answer

  1. Editorial Team

    C# Expressions

    Previously, all expressions in workflows can only be written in Visual
    Basic. In .NET Framework 4.5 RC, Visual Basic expressions are only
    used for projects created using Visual Basic. Visual C# projects now
    use C# for expressions. A fully functional C# expression editor is
    provided which capabilities such as grammar highlighting and
    intellisense. C# workflow projects created in previous versions that
    use Visual Basic expressions will continue to work.

    As of Beta 1, C# expressions are validated at design-time. Errors in
    C# expressions will be marked with a red wavy underline.

    More: What’s New in Windows Workflow Foundation in .NET 4.5

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