How to dynamically iterate/detect member types in ValueTuple that has null members?

Question

I'm trying to make use of ValueTuple to concisely enter a list of N types in a generic method's parameter list, and then later iterate that list of types.

However, I'm running into a problem when iterating the types, because the initial Tuple has null members, so calling .GetType() gives me a NullReferenceException.

I realize I could do what I need with an actual list of Type objects, but I'd prefer the very concise syntax that's allowed when creating tuples... and of course because things like this intrigue me :)

public static void IterateTupleMemberTypes<T>() where T : ITuple, new()
{
   var tuple = new T();
   for (var i = 0; i < tuple.Length; ++i)
   {
      //First call to GetType() succeeds, first element is an int.
      //Second call to GetType() fails (null ref ex), second element is a string.
      Console.WriteLine($"Item{i} Type: {tuple[i].GetType()}");
   }
}

Usage

public class CustomClass
{
   public int ID { get; set; }
}

IterateTupleMemberTypes<(int, string, CustomClass)>();

Answer 1

I think you are mixing data and metadata. The first call succeed since int is a value type, and default(int) assigns the value to 0, so it works. This won't do for reference types, since these are assigned initially to null.

I believe the proper approach here is, well, reflection - and iterating over the properties of the type, without the need to create an instance (so the new() restriction is redundant).

public static void IterateTupleMemberTypes<T>() where T : ITuple
{
    var tupleGenericArguments = typeof(T).GetGenericArguments();
    for (var i = 0; i < tupleGenericArguments.Length; ++i)
    {
        Console.WriteLine($"Item{i} Type: {tupleGenericArguments[i].Name}");
    }
}