Override ToString() to allow a custom arguments class created for the CommandLine C# library (http://github.com/gsscoder/commandline) to "reverse" itself back into an argument string. Based on code written at https://github.com/gsscoder/commandline/issues/114 by @issacg and modified to be LINQ-based by @allonhadaya

MyArguments.cs

using System;
using System.Linq;
using CommandLine;

class MyArguments {
    // Add some [Option]s here for CommandLine to use
    
    public override string ToString()
    {
        return string.Concat(this
            .GetType()
            .GetProperties()
            .Where(p => Attribute.IsDefined(p, typeof(OptionAttribute)))
            // for all properties with option attributes
            .SelectMany(p => p
                .GetCustomAttributes(typeof(OptionAttribute), inherit: true)
                .Select(a => (OptionAttribute)a)
                // get the type, name, and data
                .Select(a => new {
                    type = p.GetType(),
                    name = a.LongName,
                    data = p.GetValue(this, null)
                })
                // where data is not default
                .Where(v => v.data != ((v.type.IsValueType) ? Activator.CreateInstance(v.type) : null))
                // make an argument string
                .Select(v => string.Format("--{0} {1} ", v.name, v.data))));
    }
}