sandbox for System.CommandLine( https://github.com/dotnet/command-line-api )

SystemCommandLineSandbox.cs

using System.CommandLine;
using System.CommandLine.Binding;

var opt1 = new Option<string>(new string[]{ "--opt1", "-o1" }, "this is option1");
var opt2 = new Option<int>(new string[]{ "--opt2", "-o2" }, "this is option2");

var rootcmd = new RootCommand("this is root");
rootcmd.Add(opt1);
rootcmd.Add(opt2);
rootcmd.AddCommand(CreateCommand1());
rootcmd.SetHandler((string x, int y) =>
{
    Console.WriteLine($"opt1 = {x}, opt2 = {y}");
}, opt1, opt2);

rootcmd.Invoke(args);

Command CreateCommand1()
{
    var opt1 = new Option<string[]>("--subopt1", "this is subopt1");
    var cmd = new Command("sub1", "this is subcmd");
    cmd.AddOption(opt1);
    cmd.SetHandler<Moge>(x =>
    {
        Console.WriteLine($"opt1 = {x}");
    }, new MyBinder(opt1));
    return cmd;
}

record class Moge(string X, int Y);

class MyBinder : BinderBase<Moge>
{
    Option<string[]> _Option1;
    public MyBinder(Option<string[]> opt1)
    {
        _Option1 = opt1;
    }
    protected override Moge GetBoundValue(BindingContext bindingContext)
    {
        var value = bindingContext.ParseResult.GetValueForOption<string[]>(_Option1);
        if(value != null && value.Length > 0)
        {
            return new Moge(string.Join("|", value), value.Length);
        }
        else
        {
            return new Moge("", 10);
        }
    }
}