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I’ve been publicizing for a while that Visual Studio 11 (still in Beta) supports C# expressions in workflow designer. Of course you might also possibly want to use C# or VB expressions by writing a workflow in code, instead of by building it in Visual Studio. There are actually a couple tricks to doing...

If you’re exclusively using the Visual Studio workflow designer to design activities, you might go for a very long time (or forever) without discovering a particular System.Activities namespace, which is System.Activities.Expressions . The first reason you might never discover them is that none of the...

These questions (paraphrased) have come up a bunch of times so it’s not that hard to find the answer, but I just rediscovered them so it’s on topic for today. “I want to add a namespace to the Imports designer automatically at design time, so the user doesn’t have to do it manually. How can I do that...

Previously, I demonstrated how to use an ExpressionTextBox in a custom property editor . In this followup post, I will show how to dynamically bind the ExpressionType of the ExpressionTextBox to the type of the argument of the custom activity. We don’t provide a type converter for this out of the box...

I have fielded a couple of questions from customers and also a forum post asking how to get the binding correct for the ExpressionTextBox correct in the property grid (well Eric fielded that one with some help on our side, thanks Eric!). For the record here are the details and an explanation. WPF provides...

Oh, the imports designer . This innocuous looking piece of UI packs a lot of functionality in a little designer. You would think that this designer should be pretty straightforward. The original concept of this feature was that this would simply be the place to manage namespaces, much in the same way...

The hosted compiler does something called type coercion. It converts one type to another type using the widening and narrowing conversions specified by the big VB compiler. On the whole, this is very useful functionality. It allows you to strongly type your arguments but still set your Int16 variable...

Expressions created in the WF designer are serialized using square brackets, which is shorthand for VisualBasicValue <T> or VisualBasicReference <T>. For example, drop a WriteLine activity into a Workflow, and set its text to the expression (1+2).ToString (in VB you can omit the brackets...

Hi, today I gave a talk to our support team about the expression editing feature. Since this is all public facing information, I thought I would post the deck. Some of this information is old hat to regular readers of this blog (especially the overview and programmability bits, which I ported straight...

The Enter and Tab keys work a bit differently in the ExpressionTextBox than in the big VB IDE. In the big IDE, Enter and Tab always insert their associated characters. If the IntelliSense completion list is up, Enter selects the item and inserts a new line. We noticed that big IDE behavior does not always...

So Matt Winkler read my previous post and said hey, what about properties of type Activity<foo>, can’t they be bound to ExpressionTextBoxes too? Snap, I had forgotten about that case. The answer is actually yes, because VisualBasicValue and VisualBasicReference derive from Activity, expressions...

[12/19 edit: ExpressionTextBox is not strictly for arguments only, see the exception here ] In a previous post I alluded to the fact that you should be able to bind an ExpressionTextBox to a CLR property. My hazy memory was that this was done at one point in time by omitting the ArgumentToExpressionConverter...

The ExpressionTextBox sample code in the SDK works just fine in beta 2. The sample demonstrates the use of an ExpressionTextBox in a custom activity designer. In the sample, I implemented a simple MultiAssign activity, which assigns two values to two variables. In the example, I used untyped InArguments...

The ExpressionTextBox is the basic building block for editing expressions in custom activity designers. If you’re writing a custom activity designer that uses expressions, you’ll use this control. This post is meant to provide an overview for custom activity designer developers. I’m just going to annotate...

This is what happens when you edit an expression in Visual Studio. To simplify things, pretend you started with a blank expression. Here’s what goes on behind the scenes: When you click on an ExpressionTextBox , an instance of the hostable editor is created. As you type, you will notice two things: You...

I’ve seen a few forum posts about providing a richer expression editing experience in a rehosted workflow designer. There are two main scenarios in which you would want to implement your own expression editor: Work around the rather unfortunate limitation that the hostable editor is not available outside...

Here are the basic implementation details that you should know about the design time expression editing experience in the WF designer. An expression is bound to an activity argument or property. In the designer, the expressions are displayed inside of an ExpressionTextBox control. You can enter one single...