explanation of this c# definition: function_name(this class_name namevar)

Question

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.

I found this definition at function sin web C# applications as for example:

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

 }

[Extension Methods](http://msdn.microsoft.com/en-us/library/bb383977.aspx). — Oded, Aug 16 '12 at 13:54

mathieu · Accepted Answer · 2012-08-17T07:27:37.080

6

This is an extension method. See the following article for detailed information : http://msdn.microsoft.com/en-us/library/bb383977.aspx

Short version : this constructs enables you to make some methods available to be called on a class instance, even if you cannot (or do not) want to inherit from the class. It will not give you access to protected or private members/fields/methods.

Most notable usage : extension methods on IEnumerable / IQueryable in System.Linq namespace.

edited Aug 17 '12 at 07:27

answered Aug 16 '12 at 13:53

mathieu

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Also his question has a lot to do with ASP, hence the "Site.Web.Models.SiteIdentity" – tcables Aug 16 '12 at 13:56
1

It's worth noting that it doesn't actually add methods to a class, it just provides syntax that makes it appear as if the method was added to the class. The method itself is just a static method, even when it's an extension method. (While this doesn't seem meaningful, it really is significant.) – Servy Aug 16 '12 at 13:58

score 2 · Answer 2 · answered Aug 16 '12 at 13:55

This is an extension method for IPrincipal which returns an object of a custom type Site.Web.Models.SiteIdentity.

A principal object represents the security context of the user on whose behalf the code is running, including that user's identity (IIdentity) and any roles to which they belong.

explanation of this c# definition: function_name(this class_name namevar)

2 Answers2