Extension methods in C# 3.0

C# 3.0 introduced interesting new functionality, one of them being extension methods, which enables developers to add methods to existing types, without needing to create a new derived type (interfaces, classes, structs)

Extension methods behave much like instance methods, but have a number of limitations they can't for example access private nor protected members of the type they're extending. (I can imagine the logic behind this)

Note the following code example and how its being defined, you need a static class (all members must be static) and the first parameter of the extension method contains the "this" keyword, informing the compiler which type we're extending. (you may add numerous parameters you wish to pass to this method, but the first parameter must always define the type you want to extend)

 
public static class ExtensionMethods
{
    public static string Reverse(this string value)
    {
        char[] charArray = value.ToCharArray();
        Array.Reverse(charArray);            
        return new string(charArray);
    }
}
 

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