Revive HelperResult to allow using @helper in views

samples/MvcSample.Web/Views/Home/Create.cshtml

@@ -1,4 +1,5 @@
 @using MvcSample.Web.Models
+@using Microsoft.AspNet.Mvc.ModelBinding
 @model User
 @{
     ViewBag.Title = (Model == null) ? "Create Page" : "Edit Page";
@@ -30,12 +31,17 @@
             <ul>
                 @foreach (var property in metadata.Properties)
                 {
-                    var propertyName = property.PropertyName;
-                    var propertyTypeName = property.ModelType.Name;
-                    var propertyDescription = property.Description;
-                    <li>Property @propertyName has type @propertyTypeName and description '@propertyDescription'</li>
+                    @PropertyListItem(property)
                 }
             </ul>
         }
     }
-</div>
+</div>
+
+@helper PropertyListItem(ModelMetadata property)
+{
+    var propertyName = property.PropertyName;
+    var propertyTypeName = property.ModelType.Name;
+    
+    <li>Property @propertyName is type @propertyTypeName and '@(property.Description ?? "no description")'</li>
+}

src/Microsoft.AspNet.Mvc.Razor.Host/MvcRazorHost.cs

@@ -38,7 +38,7 @@ namespace Microsoft.AspNet.Mvc.Razor
                 writeLiteralMethodName: "WriteLiteral",
                 writeToMethodName: "WriteTo",
                 writeLiteralToMethodName: "WriteLiteralTo",
-                templateTypeName: "Template",
+                templateTypeName: "HelperResult",
                 defineSectionMethodName: "DefineSection")
             {
                 ResolveUrlMethodName = "Href"

src/Microsoft.AspNet.Mvc.Razor/RazorView.cs

@@ -97,10 +97,24 @@ namespace Microsoft.AspNet.Mvc.Razor
         {
             if (content != null)
             {
-                var htmlString = content as HtmlString;
-                var contentToWrite = htmlString != null ? content.ToString() :
-                                                          WebUtility.HtmlEncode(content.ToString());
-                writer.Write(contentToWrite);
+                var helperResult = content as HelperResult;
+                if (helperResult != null)
+                {
+                    helperResult.WriteTo(writer);
+
+                }
+                else
+                {
+                    var htmlString = content as HtmlString;
+                    if (htmlString != null)
+                    {
+                        writer.Write(content.ToString());
+                    }
+                    else
+                    {
+                        writer.Write(WebUtility.HtmlEncode(content.ToString()));
+                    }
+                }
             }
         }
 

src/Microsoft.AspNet.Mvc.Rendering/View/HelperResult.cs

@@ -0,0 +1,20 @@
+using System;
+using System.IO;
+
+namespace Microsoft.AspNet.Mvc.Rendering
+{
+    public class HelperResult
+    {
+        private readonly Action<TextWriter> _action;
+
+        public HelperResult([NotNull] Action<TextWriter> action)
+        {
+            _action = action;
+        }
+
+        public void WriteTo([NotNull] TextWriter writer)
+        {
+            _action(writer);
+        }
+    }
+}