De-/Serialization with type annotation for certain properties

[mkettn]

Hello,

is it possible to serialize and deserialize Objects with type annotation?
I know that deserialization is possible, but in a rather rough way. However, I would like to serialize for example a list of different objects with keeping their class.
Heres a sample:

using YamlDotNet.Serialization;
using YamlDotNet.Serialization.NamingConventions;
public interface Iface { public int Attr { get; set; } }
public class A : Iface { public int Attr { get; set; } }
public class B : Iface { public int Attr { get; set; } }
public class C : Iface { public int Attr { get; set; } }
public class Comp
{
    public string fixedProperty { get; set; }
    public List<Iface> attrs { get; set; } = [];
}
public class Program
{
    static public int Main(string[] args)
    {
        ISerializer? ser = new SerializerBuilder()
            .WithNamingConvention(UnderscoredNamingConvention.Instance)
            .Build();
        Comp c = new()
        {
            fixedProperty = "foo",
            attrs = [
                new A(){Attr=1},
        new B(){Attr=2},
        new C(){Attr=3},
    ]
        };
        Console.WriteLine(ser.Serialize(c));
        return 0;
    }
}

if executed, it would produce this output:

fixed_property: foo
attrs:
- attr: 1
- attr: 2
- attr: 3

however I like to produce this output:

fixed_property: foo
attrs:
- type: A
  attr: 1
- type: B
  attr: 2
- type: C
  attr: 3

this type annotation would have the advantage that I should be able load the attributes again. How can I accomplish this?
As far as i can tell this only works for deserialization as written here: https://github.com/aaubry/YamlDotNet/wiki/Deserialization---Type-Discriminators

[mkettn]

just found out that this is very similar to #847