One. Just one. VBx is the next version of Visual Basic, not a new version of Visual Basic.

Part of the confusion stems from the fact that there are TWO ways you can use Visual Basic in Silverlight, and one uses Orcas and one uses VBx. So let me see if I can clarify a little bit…

As everyone should be aware now, Silverlight is a cross-platform version of the CLR. This means that Silverlight, with some limitations, can run any compiled IL application or library that the desktop CLR can run. This also means that (again, with some limitations) Visual Basic applications or libraries that have been compiled into IL on the desktop can be downloaded and run on Silverlight. If you go and read Joe’s VB on Silverlight entry, he points you to how you can do this today–build a VB application or library using Orcas Beta 1 and then run it on Silverlight.

You’ll notice that what you have to do in this scenario, though, is compile your application or library on the desktop and then run it in Silverlight. You can’t take your application or library in source code form, send it to Silverlight and have it compiled on demand within Silverlight itself, because the Orcas Visual Basic compiler isn’t a part of Silverlight. So, for example, if I was to embed a Silverlight application in a web page viewable on the Mac, I have to build my libraries ahead of time and deploy them to the web server to be downloaded when someone hits the page.

What John and Jim demoed, and what the DLR enables, however, is a second scenario. Because the DLR is managed code, it can be run directly on Silverlight. This means that you can actually get a running instance of a DLR language within Silverlight itself. So instead of having to compile an application or library before you can use it in Silverlight, you can simply include the code as a part of the Silverlight application, and the code can be compiled by the DLR language on the fly. This enables the traditional style of client-side applications that you see in AJAX or other libraries. Instead of compiling the library ahead of time, you simply download the client code to the browser when it hits the page, and the code will be compiled and run within the browser in real time.

This is where VBx, the next version of Visual Basic, comes in. Part of VBx is a hostable managed component (written in Visual Basic, no less!) built on top of the DLR. Since Silverlight can host DLR languages, this enables you to send Visual Basic code to a Silverlight instance and have it dynamically compiled and run. So when the Mac hits your webpage, you don’t have to send a binary at all, you can send just source code. When you want to modify your application, you don’t rebuild, you just modify the source code sent to the browser and refresh the page and there you are!

The important thing to keep in mind is that there is still only ONE Visual Basic language but once VBx arrives you’ll have more than one way of getting to it. You’ll still be able to compile code into the traditional .DLL or .EXE, but you’ll also have the option of compiling and running the code on the fly, within a running instance of the CLR. That’s where things are likely to get interesting…

There was a semi-announcement as a part of the Silverlight 1.1 discussion at MIX07 yesterday that people might be wondering about.

If you check out the Silverlight poster that Brad posted a pointer to, you’ll see that on the right hand side under the box that says Framework Languages, there are TWO listings for Visual Basic. First, there’s “Visual Basic” and then down at the bottom there’s a “VBx” with a little icon “Soon.” Then, if you look at Jim Hugunin’s blog entry on the Dynamic Language Runtime (DLR), you’ll see that he says (emphasis mine):

We’re initially building four languages on top of the DLR – Python, JavaScript (EcmaScript 3.0), Visual Basic and Ruby. We shipped today both Python and JavaScript as part of the Silverlight 1.1alpha1 release today. John Lam and I will be demoing all four languages, including VB and Ruby, working together during our talk tomorrow at 11:45.

And then if you go on to Jason Zander’s blog entry on .NET Framework support in Silverlight, he says (again, emphasis mine):

With the new DLR, we have support for IronPython, IronRuby, Javascript, and the new dynamic VBx compiler.

And, finally, you can go to Amanda Silver’s entry on what the MIX07 announcements mean for the VB developer to get a few more hints.

So, what does this all mean, exactly? What is this “VBx” thing? What are we up to?

Well, as I’ve been hinting at for a while now, there’s been something I’ve been working on quite a lot in recent months that I couldn’t talk about. With our announcements at MIX07, though, I can now take a bit of the wraps off. “VBx” is our current (subject to change) codename for the next major version of Visual Basic. (The “x” is supposed to signify the Roman numeral X, or 10, since the next major version of Visual Basic is going to be 10.0. The “x” really should be capitalized, but some people were worried there’d be confusion with the old VBX controls. Not that the search engines are really going to draw a distinction. Like VB itself, they’re mostly case insensitive.)

Now, at this early stage of the game, the full shape of the next version is sketchy at best. We’re not done with Orcas by any stretch of the imagination. We haven’t even started the formal planning for process for anything beyond Orcas yet. However, there are several features that we are clear, even at this early stage of the game, that we are going to want to support in the post-Orcas timeframe:

• Visual Basic should become a hostable language that can be easily used to do application scripting, akin to what you could do with VBScript and VBA. Furthermore, this hostable language engine should be fully portable to all platforms supported by the CLR, including all platforms supported by Silverlight (such as client-side scripting in the browser on a Mac…).
• The performance of dynamic binding (a.k.a. late binding) should be as close to static binding as humanly possible.
• Dynamic method and type generation should be fully supported and consumable in the language.
• Visual Basic should fully support a REPL (Read-Eval-Print Loop). This means taking the support we already have for a REPL in the immediate window in VS and both extending it to the full language and adding the ability to host the REPL outside of Visual Studio.

If you look at this feature list, much of it is congruent with the mission of the Dynamic Language Runtime (DLR). Consequently, we’ve been working very closely with the DLR team to start prototyping many of these features in Visual Basic. If you were at the MVP summit or went to Jim and John Lam’s talk at MIX yesterday, you’ll have seen this prototype–which, again, we’re calling “VBx” for the moment–in action. Amanda and I will be working on some screencasts and other stuff to show this to the world in the near future, but it is, in essence, the fusion of the Visual Basic language services and the DLR. This gives us many of the features listed above, and more. (For example, because VBx is built on top of the DLR, it automatically interoperates with any other dynamic language built on the DLR. So VBx code can interact seamlessly with libraries written in Python, Javascript, or Ruby, and those languages can interact seamlessly with code compiled by VBx.)

As excited as we are about VBx, it is, unfortunately, not part of the Silverlight 1.1alpha1 released yesterday. Although we have a significant amount of functionality already implemented there is still more work to be done to bring the VBx language support up to the level that we feel is necessary for a productive community preview. Our plans are to have a community preview out later this year, and to talk much more detail about VBx at PDC07. In the meantime, though, we will be discussing VBx here on my blog and on the VB team blog, so keep your eyes peeled!

My +1 link postings are always the last ones in to the pool, but in case you haven’t seen it elsewhere, Beta 1 of Visual Studio Orcas is now available for download! This has a large majority of the Orcas features for VB in it, although there are still some features that will be coming in post-Beta1 (lambdas, nullable types, etc.) because of the way the schedule came together. (You can find more details about new features in Beta1, such as “Intellisense everywhere” on our team blog.)

I’ve been writing a LOT of Visual Basic code in the past couple of months, and this is making me excited to work towards getting off of VB 2005 and on to Orcas…

Check it out!

For those of you who might be curious about how the XML integration features in VB9 work, there’s now a great screencast up on Channel 9 that walks you through them while building a sample application:

The next version of VB .Net adds Xml as a built in data type using the new LINQ to XML API. As a built in data type, VB 9.0 provides the ability to create XML using XML Literals and to query XML documents using XML properties. This webcast contains a demo by David Schach, the lead developer in this project, of creating a program to share pictures over the internet.

Check it out!

Maybe you’ve seen this elsewhere, but the big news of the week (VB-wise, at least) is that the March 2007 Orcas CTP is now out. Those of you who’ve been following along with the previous Orcas CTPs will have noticed the paucity of new VB features relative to some of the other VS languages. This has been largely due to the different implementation strategies of the languages–since the Visual Basic compiler is so closely tied to the IDE services, we needed to really plumb the features all the way through before we could consider them “complete.” Anyway, many of these features are now on-line and available to be tried out. They include a bunch of features we’ve discussed before:

• Query expressions
• Object initializers
• Extension methods
• Type inference
• Anonymous types
• XML literals
• XML access members

And the CTP also includes some pretty nice Intellisense enhancements that have not been discussed previously. I encourage everyone to give the CTP a whirl and let us know what you think!

Well, I have to say that in some ways it’s great to be back at work, and in some ways, not so much. Everything’s going great at home, and now it’s time to get back into the swing of things. Two links for people who might have missed them (but I doubt many people did):

• A series by Scott Wisniewski on extension methods in VB9
• A post by Avner Aharoni on XML changes in the Feb CTP of VB9

More as I dig through my email!

One of the things we’ve been discussing for VB 9.0 is adding a true ternary operator to the language. It’s been a persistent source of annoyance for myself (and many others, to judge from suggestions and complaints we’ve gotten over the years) that there is no short-circuiting conditional expression operator in the language. True, there’s the IIF method which does most of what you want, but it doesn’t short-circuit. If you evaluate “IIF(x Is Nothing, 10, x.Foo())” and x is Nothing, then you’ll get an exception because we always evaluate all of the arguments of a method call (since IIF is just a regular method). In contrast, the C-style language’s ternary operator (i.e. “?:”, as in “x == null ? 10 : x.Foo()”) does short-circuit and it comes in mighty handy.

The annoyances get even worse with the introduction of queries into the language, because now there are a lot more places where you want to do in-line conditionals (since there aren’t statements in queries). In fact, I was a huge user of IIF back when I worked on the Access query designer in my previous life. So with LINQ coming, it’d be really nice to have a short-circuiting ternary operator available. So we’ve been pondering how best to do it. 

Rather than introduce some new operator, we’re considering doing to IIF what we did to AscW and ChrW and turning it into an intrinsic function. So even though IIF will still appear to be a function call, we’ll intercept the call and turn it into a true short-circuiting ternary operation. The nice thing is that you won’t have to learn any new syntax–things will just start working the way you expect them to. Probably 99% of programmers will never notice the change or like it. However, there probably will be that 1% of programmers (or maybe .1% of programmers or .01% of programmers) who will notice the change and be unpleasantly surprised. Perhaps you intentionally or unintentionally depended on the fact that all arguments to IIF would be evaluated, regardless of the value of the conditional expression. If so, when you recompile your application in VB 9, your program behavior will break or, even worse, silently change.

So what to do? Well, the language spec does say that we reserve the right to break compatibility for new features “only if the impact would be extremely minimal and the benefit of the feature is high.” I think, based on feedback we’ve collected, the second part of the test is no problem. The first part is the question. For example, we introduced some small compatibility breaks in the language when we added support for unsigned types (that might cause some method calls to bind to different overloads than before), but no one to date has ever reported an issue. So that’s a case where a new feature had a minimal compatibility impact and a high benefit. But what about this case?

Well, we’d like to know what people think. Our take on it is that it is extremely unlikely that anyone is consciously depending on the evaluation of both branches of the IIF expression. Extremely unlikely. And that anyone who’s unconsciously depending on the evaluation of both branches of the IIF expression is actually having a bug in their program covered up by a limitation of the language. If this is the case, then changing the behavior of IIF should help most people write more correct programs and should negatively impact very few people, if any at all.

Or will it? What’s your take?

I should also note that IIF currently doesn’t do the cute typing rules that you’d like from a ternary operator — that is, the return type of IIF is Object, so you have to cast in a lot of cases where you really shouldn’t have to. We’d also fix this at the same time (although we could also fix this by introducing a generic IIF method and fixing a few limitations of our generic inference algorithm–currently if a type parameter infers to two or more types, the algorithm fails rather than taking into account the situation where the type are all related to one another).

And one last huge CAVEAT EMPTOR: since we’re talking about pre-release software, do NOT construe this as a promise this feature will make it in to this release. Even though I believe it will get in, surprises always happen. So don’t start counting this particular chicken until you get actual bits that contain the feature. And even then, nothing’s final until we release to manufacturing.

(Bonus question: Why is it the “ternary operator?” It’s a bit of an imprecise name. An operator that takes one operand is a unary operator. An operator that takes two operands is a binary operator. And an operator that takes three operands…? Since “?:” is usually the only operator in C-style languages that takes three operands, the general “ternary operator” is applied to this specific operator. I imagine there are other names for it, this is just the one I’m used to hearing.)

In case you missed the announcement, VS 2005 SP1 is released. You can get it here. Beta support for Vista coming soon!