Dr. Dobb's Journal - February 2008 - (Page 27)

d02dino_p6ma 12/7/07 2:13 PM Page 27 The true added value of Visual Studio 2008 is the boost it gives to developer productivity The type that follows the this keyword is treated as the type to extend. Figure 3 shows IntelliSense in action on the extended System.String type. The following code illustrates how you can use these new methods in your code: void btnDate_Click(object sender, EventArgs e) { string content = textBox1.Text; if (content.IsDate()) { DateTime date = content.ToDate(); label2.Text = String.Format("Next day is {0}", date.AddDays(1).ToString("dd MMMM yyyy")); } else label2.Text = "Not a valid date."; } Extension methods are checked at compile-time and can be applied also to any parent class or interface in .NET. (Extension methods could be used to obtain a feature that looks similar to mix-ins. Overall, a mix-in is a sort of interface with implemented methods. A class that implements a mix-in includes—but not inherits—all the members on the mix-in’s interface. Currently, C# and Visual Basic .NET don’t natively support mix-ins, even though instructing the compilers to produce the code for it didn’t appear to be a huge effort. With extension methods, you can simulate mix-ins in the latest C# and Visual Basic .NET.) The var keyword is another interesting new entry. Used to qualify a variable, it doesn’t indicate a late-bound reference. Instead, it merely indicates that you don’t know the type of the variable at the time of writing. However, the type won’t be determined at runtime (late-binding), but the compiler infers the type from the expression assigned to the var variable. For this reason, an initial value assignment is required to avoid a compiler error. When var is used, a strongly typed reference is always generated. The var keyword enables another cool C# feature—the anonymous type. This is an unnamed type that you define using the same object initializer syntax mentioned earlier: var person = new { FirstName="Nancy", LastName="Davolio", Age=28 }; 9 For the CLR, anonymous and named types are exactly the same entity. Anonymous types can be used in a variety of scenarios, but have been introduced primarily to support LINQ queries. The same can be said for lambda expressions. Lambda expressions are used as a convenient way to create delegates, especially 27 February 2008 l www.ddj.com l Dr. Dobb’s Journal http://www.faircom.com/go/?usesDLD http://www.faircom.com/go/?usesDLD http://www.ddj.com

Table of Contents Feed for the Digital Edition of Dr. Dobb's Journal - February 2008

Dr. Dobb's Journal - February 2008 Contents Hmmmm Alia Vox Developer Diaries Developer’s Notebook South American Software Development Conversations Inside Visual Studio 2008 BibPort: Creating Bibliographic References Continuous LINQ The ZK Framework Static Testing C++ Code The Agile Edge Effective Concurrency Swaine’s Flames

Dr. Dobb's Journal - February 2008

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.