explanation of this c# definition: function_name(this class_name namevar)
<p>I was looking for information about this structure but i could't found it; so if someone have time to explain this or point to some URl where it's explained.</p>

<p>I found this definition at fuction sin web C# applications as for example:</p>

<pre><code>  public static class PrincipalExtensions
{
    public static Site.Web.Models.SiteIdentity SiteIdentity(this System.Security.Principal.IPrincipal principal)
    {
       .....
       }

 }
</code></pre>

<p>Thanks a lot</p>
