Is there a better name for this class?

Question

I need a version of the mvc RouteValueDictionary that I can chain Add calls to, ie:

new RouteValueDictionaryExtended()
 .AddValue("controller", "Home")
 .AddValue("action", "Index")
 .AddValue("id", 3)

Is there a more description name I can use for this instead of just "Extended"?

 public class RouteValueDictionaryExtended : System.Web.Routing.RouteValueDictionary
 {
 public RouteValueDictionaryExtended() : base() { }
 public RouteValueDictionaryExtended(object values) : base(values) { }
 public RouteValueDictionaryExtended(System.Collections.Generic.IDictionary<string,object> dict) : base(dict) { }
 public RouteValueDictionaryExtended AddValue(string key, object obj)
 {
 var newDict = new RouteValueDictionaryExtended(this);
 newDict.Add(key, obj);
 return newDict;
 }
 }

• Ivan: Two questions: 1. Maybe I miss something, but how does 'new RouteValues().WithValue("controller", "Home").WithValue("action", "Index");' returns 'RouteValues'? The return type of 'WithValue' method is 'DictionaryBuilder<RouteValueDictionary>', not 'RouteValues'. 2. What stops you from using extension methods?

Answer 1

I would actually recommend you to use the (Constructor) Builder pattern if you are only doing this for easier object initialization:

public class RouteValueDictionaryBuilder
{
 private List<Tuple<string, object>> values_ = new List<Tuple<string, object>>();
 public RouteValueDictionaryBuilder WithValue(string key, object obj)
 {
 values_.Add(Tuple.Create(key, obj));
 return this;
 }
 public RouteValueDictionary Build()
 {
 var dict = new RouteValueDictionary();
 foreach (var value in values_)
 {
 dict.Add(value.Item1, value.Item2);
 }
 return dict;
 }
}

To use:

var dict = new RouteValueDictionaryBuilder()
 .WithValue("controller", "Home")
 .WithValue("action", "Index")
 .WithValue("id", 3)
 .Build();

This avoids the higher coupling (inheritance) between the dictionary and its subclass, which is there only to help with initializing the dictionary.

Answer 2

If you need this class only to be able to chain 'Add' calls, maybe it would be better to just create an extension method:

public static class RouteValueDictionaryExtensions
{
 public static RouteValueDictionary AddValue(this RouteValueDictionary routeValueDictionary, string key, object obj)
 {
 routeValueDictionary.Add(key, obj);
 return routeValueDictionary;
 }
}

And use it like:

 new RouteValueDictionary()
 .AddValue("controller", "Home")
 .AddValue("action", "Index")
 .AddValue("id", 3);

If you still need a separate class and its only purpose is to add this chaining ability, then express it in the name like 'ChainableRouteValueDictionary' or 'FluentRouteValueDictionary'.

• asawyer: I don't think an extension method would work in my context, but I Fluent was exactly what I was looking for thank you!