Note, as per the comment, I’d just like to point out that I too recommend using a real type when you need to pass it around the program like this. Anonymous types should only really be used locally in a single method at a time (in my opinion), but anyway, here’s the rest of my answer.
You can do it using a trick, by tricking the compiler into inferring the right type for you:
using System;
namespace ConsoleApplication4
{
class Program
{
static void Main(string[] args)
{
var a = new { Id = 1, Name = "Bob" };
TestMethod(a);
Console.Out.WriteLine("Press enter to exit...");
Console.In.ReadLine();
}
private static void TestMethod(Object x)
{
// This is a dummy value, just to get 'a' to be of the right type
var a = new { Id = 0, Name = "" };
a = Cast(a, x);
Console.Out.WriteLine(a.Id + ": " + a.Name);
}
private static T Cast<T>(T typeHolder, Object x)
{
// typeHolder above is just for compiler magic
// to infer the type to cast x to
return (T)x;
}
}
}
The trick is that inside the assembly, the same anonymous type (same properties, same order) resolves to the same type, which makes the trick above work.
private static T CastTo<T>(this Object value, T targetType)
{
// targetType above is just for compiler magic
// to infer the type to cast value to
return (T)value;
}
usage:
var value = x.CastTo(a);
But we’re really pushing the limits here. Use a real type, it’ll look and feel cleaner as well.