Jack @ ASP.NET

ASP.NET MVC 2 is a framework for developing highly testable and maintainable Web applications by leveraging the Model-View-Controller (MVC) pattern. The framework encourages developers to maintain a clear separation of concerns among the responsibilities of the application – the UI logic using the view, user-input handling using the controller, and the domain logic using the model. ASP.NET MVC applications are easily testable using techniques such as test-driven development (TDD).
The installation package includes templates and tools for Visual Studio 2008 SP 1 to increase productivity when writing ASP.NET MVC applications. For example, the Add View dialog box takes advantage of customizable code generation (T4) templates to generate a view based on a model object. The default project template allows the developer to automatically hook up a unit-test project that is associated with the ASP.NET MVC application.
Because the ASP.NET MVC framework is built on ASP.NET 3.5 SP 1, developers can take advantage of existing ASP.NET features like authentication and authorization, profile settings, localization, and so on. Download it at: http://www.microsoft.com/downloads/details.aspx?FamilyID=7aba081a-19b9-44c4-a247-3882c8f749e3&displaylang=en

What is new:

• The new ASP.NET MVC 2 validation feature now performs model-validation instead of input-validation (this means that when you use model binding all model properties are validated instead of just validations on changed values of a model).  This behavior change was based on extensive feedback from the community.

• The new strongly-typed HTML input helpers now support lambda expressions which reference array or collection indexes.  This means you can now write code like Html.EditorFor(m=>m.Orders[i]) and have it correctly output an HTML <input> element whose “name” attribute contains the index (e.g. Orders[0] for the first element), and whose “value” contains the appropriate value.

• The new templated Html.EditorFor() and Html.DisplayFor() helper methods now auto-scaffold simple properties (and do not render complex sub-properties by default).  This makes it easier to generate automatic scaffolded forms.  I’ll be covering this support in a future blog post.

• The “id” attribute of client-script validation message elements is now cleaner.  With RC1 they had a form0_ prefix.  Now the id value is simply the input form element name postfixed with a validationMessage string (e.g. unitPrice_validationMessage).

• The Html.ValidationSummary() helper method now takes an optional boolean parameter which enables you to control whether only model-level validation messages are rendered by it, or whether property level validation messages are rendered as well.  This provides you with more UI customization options for how validation messages are displayed within your UI.

• The AccountController class created with the default ASP.NET MVC Web Application project template is cleaner.

• Visual Studio now includes scaffolding support for Delete action methods within Controllers, as well as Delete views (I always found it odd that the default T4 templates didn’t support this before).

• jQuery 1.4.1 is now included by default with new ASP.NET MVC 2 projects, along with a –vsdoc file that provides Visual Studio documentation intellisense for it.

• The RC2 release has some significant performance tuning improvements (for example: the lambda based strongly-typed HTML helpers are now much faster).

XML to be operated on:

   1: <States>

   2:   <State name="Wisconsin">

   3:     <Regions>

   4:       <Region name="Milwaukee">

   5:         <Area name="Mukwanago"/>

   6:         <Area name="Germantown"/>

   7:       </Region>

   8:       <Region name="Fox Valley">

   9:         <Area name="Oshkosh" />

  10:         <Area name="Appleton" />

  11:       </Region>    

  12:     </Regions>

  13:   </State>

  14: </States>

C# code:

   1: // using System.Xml.Linq

   2:  

   3: // make sure the xml file exists

   4: XElement states  = XElement.Load("testXML.xml");

   5:  

   6: // Using LINQ

   7: XElement foundNode;

   8: var query = from XElement r in states.Descendants("Region")

   9:                    where r.Attribute("name").Value == "Milwaukee"

  10:                    select r;

  11: foundNode = query.FirstOrDefault();

  12:  

  13: // Using Lambda expressions

  14: foundNode = states.Descendants("Region").

  15:      Where(r => r.Attribute("name").Value ==

  16:                          "Milwaukee").FirstOrDefault(); 

A polyglot is a computer program or script written in a valid form of multiple programming languages, which performs the same operations or output independently of the programming language used to compile or interpret it.

Generally polyglots are written in a combination of C (which allows redefinition of tokens with a preprocessor) and a scripting programming language such as Lisp, Perl or sh.

For the past few years, many industry leaders were saying that developers needed to know multiple languages. They were right, because learning multiple languages (if done correctly) meant that you needed to learn different programming idioms: procedural programming, object oriented programming, functional programming, and so on.

But that’s painful. Why should I need to learn new syntax to use new idioms? Curly braces aren’t allowed in FP? semicolons aren’t permitted in dynamic languages?

Instead, why can’t a general purpose programming language support multiple programming idioms? C#, VB.NET, and C++ are starting to seriously support that. (Other languages may be doing this as well; I don’t know). All these languages have added (or are adding) lambda expressions which support functional programming concepts. (C++ has used Class Type Functors for this purpose for some time). C# is adding support for dynamic typing (as is VB.NET, in a more strict fashion than previously supported). Implicit typing is supported in C#, C++, and VB.NET as well.

This trend will continue as more and more developers want to use the best programming idiom for a particular task without learning a totally different syntax. Any programming language that calls itself a “general purpose language” will support multiple idioms.