这是MVC3中的扩展或帮助方法吗？

Question

I am confused about which is which. Can someone explain the difference between the two.

For example is the following which returns a MvcHtmlString an extension or a helper method?

public static class LinkExtensions
{
    public static MvcHtmlString HdrLinks(
        this HtmlHelper helper, 
        string topLink, 
        string subLink, 
        System.Security.Principal.IPrincipal user)
    {
    etc ...

How about this:

    public static class Slug
{
    public static string Generate(string phrase, int maxLength = 50)
    {
        string str = RemoveAccent(phrase).ToLower();
        str = Regex.Replace(str, @"[^a-z0-9\s-]", " ");
        str = Regex.Replace(str, @"[\s-]+", " ").Trim();
        str = str.Substring(0, str.Length <= maxLength ? str.Length : maxLength).Trim();
        str = Regex.Replace(str, @"\s", "-");
        return str;
    }

Answer 1

They are not helper methods, they are called HTML helpers.There is no 'helper method' implementation in C#. HTML helpers are implemented as extension methods. You can see extension methods are static methods with a this clause before first parameter. HTML helpers makes it easier to generate html tags.

Answer 2

public static MvcHtmlString HdrLinks(this HtmlHelper helper, string topLink)

is both a C# extension method and an html helper method for use in ASP.NET MCV Views:

//Example of a call as an extension method:

var helper = new HtmlHelper(...);
var result = helper.HdrLinks(topLink);

//Example of a call as a helper method in an MVC razor view:
@Html.HdrLinks(topLink)

The following is a "standard" static C# method:

public static class Slug {
  public static string Generate(string phrase, int maxLength = 50)
}

//Example of call:

var phrase = "Freech Alpes are the surfer's best spot"
var result = Slug.Generate(phrase);

Static methods are called without a class instance. It is a special dummy construct to group functions.