A generic list of anonymous class

Question

In C# 3.0 you can create anonymous class with the following syntax

var o = new { Id = 1, Name = "Foo" };

Is there a way to add these anonymous class to a generic list?

Example:

var o = new { Id = 1, Name = "Foo" };
var o1 = new { Id = 2, Name = "Bar" };

List<var> list = new List<var>();
list.Add(o);
list.Add(o1);

Another Example:

List<var> list = new List<var>();

while (....)
{
    ....
    list.Add(new {Id = x, Name = y});
    ....
}

Answer 1

Yes, you can say List<object> and things will work. However, list[0].Id won't work. This will work in C# 4.0 by having a List<dynamic>.

UPDATE: As mentioned in the comments, this List<dynamic> trick won't get you IntelliSense, but it will work at runtime.

Answer 2

Check out this example for creating/using Lists with anonymous classes.

Answer 3

You could do:

var list = new[] { o, o1 }.ToList();

There are lots of ways of skinning this cat, but basically they'll all use type inference somewhere - which means you've got to be calling a generic method (possibly as an extension method). Another example might be:

public static List<T> CreateList<T>(params T[] elements)
{
     return new List<T>(elements);
}

var list = CreateList(o, o1);

You get the idea :)

Answer 4

I guess

List<T> CreateEmptyGenericList(T example) {
    return new List<T>();
}

void something() {
    var o = new { Id = 1, Name = "foo" };
    var emptyListOfAnonymousType = CreateEmptyGenericList(o);
}

will work.

Answer 5

You can do it this way:

var o = new { Id = 1, Name = "Foo" };
var o1 = new { Id = 2, Name = "Bar" };

var array = new[] { o, o1 };
var list = array.ToList();

list.Add(new { Id = 3, Name = "Yeah" });

It seems a little "hacky" to me, but it works - if you really need to have a list and can't just use the anonymous array.

Answer 6

This issue would of course be solved by allowing the language to define an anonymous class as implementing an interface - java style. This is something I find lacking on an almost daily basis.. Drunken monkeys came up with the crap we know as C# anonymous classes. Why is MS implementing new features when the old features are so half assed?

Answer 7

It is too late to in this thread, but useful for viewers who want this in future. here is the answer. thanks, Dutt

        string result = String.Empty;

        var list = new[] { 
                            new { Number = 10, Name = "Smith" },
                            new { Number = 10, Name = "John" } 
                         }.ToList();
        foreach (var item in list)
        {
            result += String.Format("Name={0}, Number={1}\n", item.Name, item.Number);
        }

        MessageBox.Show(result);