HtmlHelper methods and RouteValueDictionary - asp.net-mvc

Question

When writing an htmlhelper extension if I want to support the similarly structured ctors for my htmlhelper extension method, I use RouteValueDictionary as follows:
public static string ListBoxDict(this HtmlHelper htmlHelper,
string name,
object value,
object htmlAttributes)
{
return ListBoxDict(htmlHelper,
name,
value,
((IDictionary<string, object>)
new RouteValueDictionary(htmlAttributes)));
}
My question really is why the need for RouteValueDictionary ... I know you can't just cast the htmlAttributes to IDictionary<string, object> ... though I'm not sure why and that might be where I'm confused. Shouldn't RouteValueDictionary be to do with Routing and therefore nothing to do with HtmlHelper methods? Like I say, I'm probably missing the point so I'd be glad if someone could tell me what I've missed.
Cheers...
edit: in response to Dan's answer -->
I was just following what I had seen in use in the mvc source code for input helpers...
see "src\SystemWebMvc\Mvc\Html\InputExtensions.cs"
It does as follows:
public static string TextBox(this HtmlHelper htmlHelper,
string name,
object value,
object htmlAttributes)
{
return TextBox(htmlHelper,
name,
value,
new RouteValueDictionary(htmlAttributes))
}
Clearly a shortcut but is it a bastardization or is it ok to do it?

Answer 1

I would strongly recommend looking at Rob Conery's blog post about something like this.
The meat and veg of it is this:
Codedump:
public static string ToAttributeList(this object list)
{
StringBuilder sb = new StringBuilder();
if (list != null)
{
Hashtable attributeHash = GetPropertyHash(list);
string resultFormat = "{0}=\"{1}\" ";
foreach (string attribute in attributeHash.Keys)
{
sb.AppendFormat(resultFormat, attribute.Replace("_", ""),
attributeHash[attribute]);
}
}
return sb.ToString();
}
public static string ToAttributeList(this object list,
params object[] ignoreList)
{
Hashtable attributeHash = GetPropertyHash(list);
string resultFormat = "{0}=\"{1}\" ";
StringBuilder sb = new StringBuilder();
foreach (string attribute in attributeHash.Keys)
{
if (!ignoreList.Contains(attribute))
{
sb.AppendFormat(resultFormat, attribute,
attributeHash[attribute]);
}
}
return sb.ToString();
}
public static Hashtable GetPropertyHash(object properties)
{
Hashtable values = null;
if (properties != null)
{
values = new Hashtable();
PropertyDescriptorCollection props =
TypeDescriptor.GetProperties(properties);
foreach (PropertyDescriptor prop in props)
{
values.Add(prop.Name, prop.GetValue(properties));
}
}
return values;
}
Usage:
public static string ListBoxDict(this HtmlHelper htmlHelper,
string name,
object value,
object htmlAttributes)
{
return htmlHelper.ListBoxDict(name,
value,
htmlAttributes.ToAttributeList()));
}
What .ToAttributeList() does is convert your htmlAttribute object to
name = "value"
Hope this makes sense.