.net 4.0 - HtmlString vs. MvcHtmlString

Question

HtmlString vs. MvcHtmlString

What are the differences bettween those two, or when to prefer one over the other?

Edit:

One thing to prefer MvcHtmlString over HtmlString is the extension method IsNullOrEmpty of MvcHtmlString.

Answer 1

HtmlString only exists in ASP.NET 4.

MvcHtmlString was a compatibility shim added to MVC 2 to support both .NET 3.5 and .NET 4. Now that MVC 3 is .NET 4 only, it's a fairly trivial subclass of HtmlString presumably for MVC 2->3 for source compatibility.

If you're ever going to drop back to MVC 2 it might make sense to use IHtmlString or var for values returned from MVC functions. Alternatively I think you can now just switch to HtmlString throughout.