* What's New in CSharp 3.0

Here is a point wise summary of features introduced newly in C# 3.0

Implicitly Typed Local Variables

• Local variables can be declared as type ‘var’ which means compiler to determine the actual type based on the data by which its is initialized.
• var i = 10; // i is created of type int
• var name = “MyName” ; // name is created of type string
• can only be used when declared and initialized in same statement.
• Cannot be initialized to null.
• Cannot be used as class members.
• Mostly used to store anonymous types as in LINQ based programming.

Object & Collection Initializers

• Allow assigning values to any accessible members or properties of a type at the time of initiation without invoking the constructor with parameters.
• The default constructor gets executed before assigning the values.
• E.g. Coordinate c1 = new Coordinate {x=1 , y=2};
• Used in LINQ query expressions along with anonymous types.
• Collection Initializers use Object Initializers to specify multiple elements of collection without calling Add method multiple times.

Extension Methods

• Allows adding new methods to existing types without modifying the existing type.
• Are special kind of static methods but are called as if they are instance methods.
• The first parameter passed to Extension methods specifies to which type they operate on preceded by ‘this’ keyword.
• They cannot access the private variables of type which they are extending.
• Extension Methods need to defined in a non-nested and non-generic static class.
• Instance methods take priority over extension methods in case they have same signature.

Anonymous Types

• Are of class types which can have only public read-only properties as their members. No other class members like methods are allowed.
• They are of reference types and are derived from ‘Object’ class.
• Internally compiler gives them the name but its not accessible by application code.
• They have a method scope.
• Can be initiated directly e.g. new { property1=1, property2=”Hello World”};

Lambda Expressions

• Very similar to anonymous methods introduced in C# 2.0.
• Its an inline expression or statement block which can be used to pass arguments to method call or assign value to delegate.
• All lambda expression use lambda operator => where the left side denotes result and right contains statement block or expression.

Auto-Implemented Properties

• Helps in simplifying property declaration in cases where there is no custom logic required in accessors methods.
• E.g. public int Price {get; set;};
• Internally compiler creates an anonymous field for assigning values.

In my next post on this i will demonstrate these using a code sample.

Other Posts

• LINQ : An Introduction
• ADO.NET : Past, Present & Future
• Performance Analysis/Tuning of ASP.NET Application
• Auto Performance Tuning in ASP.NET 2.0
• Overview of Interoperability with UnManaged world
• Tutorial : Perform Web Load testing using Visual Studio
• Tip : How to change the default assembly information