C# -Interview Question Anonymous Type

Question

Recently i was asked to prove the power of C# 3.0 in a single line( might be tricky)

i wrote

new int[] { 1, 2, 3 }.Union(new int[]{10,23,45}).
ToList().ForEach(x => Console.WriteLine(x));

and explained you can have (i) anonymous array (ii) extension method (iii)lambda and closure all in a single line.I got spot offer.

But.....

The interviewer asked me how will you convert an anonymous type into known type :(

I explained

public class Product
{
    public double ItemPrice { private set; get; }
    public string ItemName { private set; get; }
}


var anony=new {ItemName="xxxx",ItemPrice=123.56};

you can't assign product a=anony;

The interviewer replied there is 200% chance to do that if you have a small work around.I was clueless.

As usual,I am waiting for your valuable reply(Is it possible?).

Answer 1

You're right, you can't make this assignment:

product a=anony;

MSDN: Anonymous Types (C# Programming Guide)

An anonymous type cannot be cast to any interface or type except for object.

Answer 2

Maybe something like this:

class Program
{
    static T Cast<T>(object target, T example)
    {
        return (T)target;
    }

    static object GetAnon()
    {
        return new { Id = 5 };
    }

    static void Main()
    {
        object anon = GetAnon();
        var p = Cast(anon, new { Id = 0 });
        Console.WriteLine(p.Id);
    }
}

Remark: never write or rely on such a code.