With the new Razor View Engine, should my HtmlHelp

With the Razor View Engine, anytime you output a string directly to the page, it's HTML encoded. e.g.:

@"<p>Hello World</p>"

will actually get output to the page as:

&lt;p&gt;Hello World &lt;/p&gt;

Which would show up in the browser as:

<p>Hello World </p>

Here's the problem though, when creating Html helpers, till now, with the old aspx view engine I would just return a string, and output that to the browser:

<%= Html.MyCoolHelperMethod(); %>

So my question is basically this. Do I do this:

public static IHtmlString MyCoolHelperMethod(this HtmlHelper helper)
{
   return new helper.Raw("<p>Hello World</p>");
}

in which case I can just do this in my cshtml:

@Html.MyCoolHelperMethod();

or do I do this:

public static string MyCoolHelperMethod(this HtmlHelper helper)
{
   return "<p>Hello World</p>";
}

in which case I need to do the work in my cshtml:

@Html.Raw(Html.MyCoolHelperMethod());

Obviously the first approach makes the view look a lot cleaner, but I'm just wondering if the common pattern is in fact for helpers to return an IHtmlString and I've been doing it wrong in the past.

In most cases you should return an instance of IHtmlString. That's the pattern followed by the built-in helpers* and it means that the consumer of a helper does not need to worry about under- or over-encoding.

Instead of using the Raw function you should probably just return a new instance of HtmlString.

public static IHtmlString MyCoolHelperMethod(this HtmlHelper helper) {
    return new HtmlString("<p>Hello World</p>");
}

*Note that MVC 3 actually uses MvcHtmlString as the return type of its helpers but this is a holdover from the MVC 2 days. (Complicated story, but in short, IHtmlString was only introduced in .NET 4 and since MVC 2 supported .NET 3.5 the MvcHtmlString type was introduced as an intermediate step). All helpers targetting MVC 3 and higher should return IHtmlString.