Other than for LINQ queries, how do you use anonymous types in C#?

Question

I've been trying to get up to speed on some of the newer features in C# and one of them that I haven't had occasion to use is anonymous types.

I understand the usage as it pertains to LINQ queries and I looked at this SO post which asked a similar question. Most of the examples I've seen on the net are related to LINQ queries, which is cool. I saw some somewhat contrived examples too but not really anything where I saw a lot of value.

Do you have a novel use for anonymous types where you think it really provides you some utility?

Answer 1

With a bit of reflection, you can turn an anonymous type into a Dictionary<string, object>; Roy Osherove blogs his technique for this here: http://weblogs.asp.net/rosherove/archive/2008/03/11/turn-anonymous-types-into-idictionary-of-values.aspx

Jacob Carpenter uses anonymous types as a way to initialize immutable objects with syntax similar to object initialization: http://jacobcarpenter.wordpress.com/2007/11/19/named-parameters-part-2/

Anonymous types can be used as a way to give easier-to-read aliases to the properties of objects in a collection being iterated over with a foreach statement. (Though, to be honest, this is really nothing more than the standard use of anonymous types with LINQ to Objects.) For example:

Dictionary<int, string> employees = new Dictionary<int, string>
{
    { 1, "Bob" },
    { 2, "Alice" },
    { 3, "Fred" },
};

// standard iteration
foreach (var pair in employees)
    Console.WriteLine("ID: {0}, Name: {1}", pair.Key, pair.Value);

// alias Key/Value as ID/Name
foreach (var emp in employees.Select(p => new { ID = p.Key, Name = p.Value }))
    Console.WriteLine("ID: {0}, Name: {1}", emp.ID, emp.Name);

While there's not much improvement in this short sample, if the foreach loop were longer, referring to ID and Name might improve readability.

Answer 2

ASP.NET MVC routing uses these objects all over the place.