Head over to Channel9 to read more about the official release. The setup package (available here) contains the components for .NET 3.5 SP1, .NET 4, Silverlight 4 and Windows Phone 7.
[Updated on 02 Jul 11 after the Rx official release: Renamed Run to ForEach]
[If you don’t know what Ix (Interactive Extensions for .NET) is, then I recommend reading my earlier post.]
There are very good resources (like this video) on Ix operators so I am not going to spend too much time on this but I am going to talk about a few of these operators (my top three) to show how the interactive extensions can make your code easier to write and read.
I will use unit tests to express the functionality I am expecting and will then provide potential solutions without using Ix, and finally showing how Ix would simplify the implementation.
For the code snippets, assume that all methods (excluding the test methods) live in a static class named MyEnumerableScrathPad.
You have an object of type T and want an enumerable sequence of T, which includes that object only.
[TestMethod]
public void ReturnTest()
{
var item = new object();
var returnedItem = MyEnumerableScratchPad.Return(item).Single();
Assert.AreSame(item, returnedItem);
}
public static IEnumerable<T> Return<T>(T item)
{
return new T[] { item };
}
public static IEnumerable<T> Return<T>(T item)
{
return EnumerableEx.Return(item);
}
You have an enumerable sequence of T and you want to add an instance of type T to the beginning of that sequence.
[TestMethod]
public void StartWithTest()
{
var count = 10;
var zero = 0;
var originalRange = Enumerable.Range(1, count);
var newRange = MyEnumerableScratchPad.StartWith(originalRange, zero);
Assert.AreEqual(zero, newRange.First());
Assert.AreEqual(count + 1, newRange.Count());
}
public static IEnumerable<T> StartWith<T>(IEnumerable<T> originalSequence,
T first)
{
var list = originalSequence.ToList();
list.Insert(0, first);
return list.AsEnumerable();
}
This will make the test pass but this implementation may force you to iterate through the items unnecessarily because of the call to ToList. We were also lucky that this implementation passed the test. If you change the value of count from 10 to int.MaxValue – 1, the test will horribly fail with an OutOfMemoryException. So the idea of converting the enumerable to a list is not a good one.
public static IEnumerable<T> StartWith<T>(IEnumerable<T> originalSequence,
T first)
{
yield return first;
foreach (var item in originalSequence)
yield return item;
}
This implementation does not suffer from the problem shown above and passes the test after a fairly long delay (around 10 seconds on my laptop), which is expected as a result of the call to Count, which will iterate through the sequence and one can argue that this is not a good test but it fits the purpose here.
public static IEnumerable<T> StartWith<T>(IEnumerable<T> originalSequence,
T first)
{
return originalSequence.StartWith(first);
}
Ix also has another overload for StartWith, which takes a param array of items to be inserted at the beginning of the sequence, which can be handy.
You have an enumerable sequence and you want to perform an action for each item of the sequence.
[TestMethod]
public void ForEachTest()
{
var list = new List<int>();
var range = Enumerable.Range(1, 10);
MyEnumerableScratchPad.ForEach(range, list.Add);
CollectionAssert.AreEqual(range.ToList(), list);
}
public static void ForEach<T>(IEnumerable<T> sequence, Action<T> action)
{ foreach (var item in sequence)
{
action(item);
}
}
Clearly this is a valid solution but we are looking for a more compact solution.
public static void ForEach<T>(IEnumerable<T> sequence, Action<T> action)
{
Array.ForEach(sequence.ToArray(), action);
}
public static void ForEach<T>(IEnumerable<T> sequence, Action<T> action)
{
sequence.ToList().ForEach(action);
}
Implementations #2 and #3 are not ideal as they both force the enumeration of the sequence before the iterating through the items begins. This is not necessarily a problem but there are some cases where you want to perform the action as soon as the sequence yields a new value.
public static void ForEach<T>(IEnumerable<T> sequence, Action<T> action)
{
sequence.ForEach(action);
}
Because most of the Ix operators including ForEach are ported back from the Rx world, there are some interesting additional overloads for ForEach. For example, there is one that takes action of T (the action that needs to be performed on each item) and then another action that will be performed when the iteration over the sequence is completed.
These three operators (Return, StartWith and ForEach) are among the simplest of the long list of Ix operators but nonetheless they are the ones I use most as they make code more concise and easier to read.
[Updated on 02 Jul 11 after the Rx official release]
I have to start this post with a clarification: “Ix” is not the name of an official product. I am just calling it so to highlight the benefits of this less known part of the Reactive Extensions or “Rx” (which is a real product by the way).
Interactive Extensions used to be part of the Rx library but they can now be downloaded separately. Rx is now officially released and the stable version can be downloaded from here. Ix is now packaged separately and its experimental release can be downloaded from here. Both of these components are also available on the main Nuget feed.
Even many developers who are using Rx are unaware of this interactive part of the library and I believe it deserves more attention. But let’s start with Rx, just in case you don’t know what it is.
Rx is a library developed by Microsoft, which allows you to write applications that react to events using a nice and clean implementation of the observable pattern. Rx started off as a Microsoft DevLabs incubation project but it proved to be very popular so its incubation period was ended in April 2011 and since then, it has been moved to the MSDN Data Developer Center.
I refer to the interactive part of the Rx product family as “Ix”, which deals with enumerable sequences (IEnumerable<T>) whereas Rx focuses on the observable sequences (Observable<T>).
If you have watched Inside the Rx video on Channel9 or read Bart De Smet’s blog post on this topic, you already know that enumerable sequences are the duals of the observable sequences. When the Rx team created the operators for the observable sequences, they also back ported some of those operators to the enumerable world and that is how Ix was born.
The following diagram shows the dependencies between major Rx and Ix components. Note that the reactive extensions come with a few more assemblies (related to async support, client profile and more) which are not displayed here.
So like Rx, Ix takes a dependency on:
- CoreEx: Providing the core functionality such as a selection of helpers for disposable objects, schedulers and concurrent data structures.
- System.Observable: Containing IObservable<T> and IObserver<T> interfaces. [Not applicable to .NET 4.0 as it is included in mscorlib 4.0]
The pre-release versions of the Rx product family consisted of various components such as System.Reactive, System.Interactive, CoreEx and System.Observable (for all runtimes except .NET 4.0). In the official release, the component structure is simplified and there are only two assemblies involved: System.Reactive and System.Interactive. All of the types required by those assemblies are now embedded in so for example, the IObservable and IObserver interfaces for runtimes other than .NET 4 now live inside System.Reactive. Same applies to the disposable and scheduler types.
If you are not using Rx family for whatever reason, it is now a good time to do so. I will go as far as saying:
If you are a .NET developer, then you should be using Rx and/or Ix in your projects or you are doing something wrong!
You might say I am taking it too far but I insist! If you are using Rx already, then you know what I am talking about. If you aren’t, you will know it when you start using it. Rx targets various platforms and frameworks including .NET (3.5, 4.0 for both client and full profiles), Silverlight (3, 4, 5), Windows Phone, Xbox and Javascript so you can use it in any .NET project.
These extensions can be downloaded by following the links on the product landing page on MSDN. You can also find a variety of Rx and Ix components on the official Nuget feed.
The primary type in Ix is the EnumerableEx type, which adds a long list of operators (in the form of extension methods) to IEnumerable<T>, plus a few operators for enumerable sequence of numbers (to support average, min, max, etc).When developers look at the list of operators provided by these extensions, most people ask “Why aren’t these included in .NET Framework anyway?”. I think (and hope) that this is just a matter of time before they make their way into the framework. Once you start using these extensions, you will soon find out that you cannot live without them, especially if you use LINQ frequently.
In the next post, I will briefly go through some of the Ix operators to show how it can help you in writing code that is easier to write and read.
This is a link post with links to tutorials, samples and training courses covering the recent releases of Microsoft’s development platform tools and technologies.
Visual Studio 2010 and .NET Framework 4 Training Kit (June 2010)
Covers:
Identity Developer Training Kit (June 2010)
Covers:
Windows Azure Training Kit (June 2010)
Covers:
Windows Server AppFabric Samples (June 2010)
Covers:
Silverlight 4 Training (April 2010)
Covers:
The RTM version of Visual Studio 2010 and Team Foundation Server 2010 is now available for download as a virtual machine. The VM image also include a sample application and sample data to support the accompanying hands on labs. This image does not include the Visual Studio Lab Management 2010 but the team are working on it.
The virtual machine image comes in multiple flavours to support these virtualization technologies: Hyper-V, Windows Virtual PC (for Windows 7) and Virtual PC 2007 SP1. All of these images will expire on 15 Dec 2010.
Refer to Brian Keller’s post for additional details.
Windows Server AppFabric simplifies the process of creating, scaling and managing web and composite applications that run on IIS and includes the following components:
You can get the RTW bits using the Web Platform Installer or downloading it directly from here.
The supported operating systems are both 32-bit and 64-bit editions of:
You will also need a version of .NET Framework, depending on the features you want to use (more info):
There are a number of additional resources linked from the landing page, including the Windows Server AppFabric wiki.
As planned, VSTS 2010 Team Suite Beta 1, .NET Framework 4 Beta 1, TFS 2010 Beta 1 and VSTS 2010 Test Load Agent and Controller Beta 1 are now available for download from MSDN Subscribers area.
We now have 32-bit and 64-bit support for TFS and the TFS client OM. All of the client tools such as Visual Studio will continue to run in 32-bit environment though. For more information on the supported environments for TFS and the improvements in setup, administration and operations refer to Brian Harry’s post.
Earlier today, we announced the next wave of developer products and tools, namely Visual Studio 2010 and .NET Framework 4.0. Both of these products are major releases that bring new concepts and paradigms to the software development and introduce new first class citizens to the Visual Studio environment. The result will be an ever higher productivity for the development teams and lower barrier to entry for developing applications for various products and technologies we offer today and will ship within the next few years.
The focus of the first annoncement is on VSTS 2010 (code-named “Rosario”) and the improvements to the ALM process. My favourite enhancements are:
This is not an exhaustive list but these are the items that caught my eyes as I was reading the announcement. There is also a (good!) change in the product licensing for VSTS, which is great news for the development teams. Since I don’t want you to miss this announcement, I am going to write a separate post on this subject.
As you can imagine, there are loads of more features to come with Visual Studio 2010 and .NET Framework 4.0. If you are going to the PDC, you will be lucky enough to hear about it all the time but if you aren’t, make sure you follow the news on the blogosphere and the PDC official web site.
Additional resources:
- VSTS 2010 on Channel9
- VSTS 2010 and .NET Framework 4.0 Overview on MSDN
