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Clarion.Net supports using and declaring extension methods. To declare extension methods use the **Extension** attribute.

Extension methods enable you to "add" methods to existing types without creating a new derived type, recompiling, or otherwise modifying the original type. Extension methods are a special kind of static method, but they are called as if they were instance methods on the extended type. For client code written in Clarion#, there is no apparent difference between calling an extension method and the methods that are actually defined in a type.

The most common extension methods are the LINQ (Language Integrated Query) standard query operators that add query functionality to the existing **System.Collections.IEnumerable** and **System.Collections.Generic.IEnumerable** types. To use the standard query operators, first bring them into scope with a //using System.Linq// directive. Then any type that implements **IEnumerable** appears to have instance methods such as //GroupBy//, //OrderBy//, //Average//, etc.

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**LINQ support requires that you have Net Framework 3.5 installed.**

**The ****System.Core assembly and the corresponding USING statements are needed for the [Extension] attribute.**

**Example:**

**   PROGRAM**

**    USING System.Linq**

**    USING System.Core**

**    USING System.Collections.Generic**

**    USING System.Runtime.CompilerServices**

**    NAMESPACE qq**

** [Extension]**

**dd CLASS,STATIC,PUBLIC**

** [Extension]**

**mm PROCEDURE(SIGNED aa),STATIC,PUBLIC**