// @nuget: CommandLineParser -Version 2.8.0

using System;

using System.Collections.Generic;

using CommandLine;

using CommandLine.Text;

​

public class Program

{

    public static void Main()

    {

        var args = "--help".Split();

        Console.WriteLine("Re-ordering options using  RequiredThenAlphaComparison");

        StartUp(args);

    }

​

    static void StartUp(string[] args)

    {

        var parser = new CommandLine.Parser(with => with.HelpWriter = null);

        var parserResult = parser.ParseArguments<Options>(args);

        parserResult.WithParsed<Options>(options => Run(options)).WithNotParsed(errs => DisplayHelp(parserResult, errs));

    }

​

    static void DisplayHelp<T>(ParserResult<T> result, IEnumerable<Error> errs)

    {

        var helpText = HelpText.AutoBuild(result, h =>

        {

            h.OptionComparison = HelpText.RequiredThenAlphaComparison;

            //h.OptionComparison = orderOnShortName;

            return h;

        }

​

        , e => e);

        Console.WriteLine(helpText);

    }

​

    static void Run(Options options)

    {

    //do stuff      

    }

​

    static Comparison<ComparableOption> orderOnShortName = (ComparableOption attr1, ComparableOption attr2) =>

    {

        if (attr1.IsOption && attr2.IsOption)

        {

            if (attr1.Required && !attr2.Required)

            {

                return -1;

            }

            else if (!attr1.Required && attr2.Required)

            {

                return 1;

            }

            else

            {

                if (string.IsNullOrEmpty(attr1.ShortName) && !string.IsNullOrEmpty(attr2.ShortName))

                {

                    return 1;

                }

                else if (!string.IsNullOrEmpty(attr1.ShortName) && string.IsNullOrEmpty(attr2.ShortName))

                {

                    return -1;

                }

​

                return String.Compare(attr1.ShortName, attr2.ShortName, StringComparison.Ordinal);

            }

        }

        else if (attr1.IsOption && attr2.IsValue)

        {

            return -1;

        }

        else

        {

            return 1;

        }

    }

​

    ;

}

​

class Options

{

    [Option('r', "read", Required = false, HelpText = "Input files to be processed.")]

    public IEnumerable<string> InputFiles

    {

        get;

        set;

    }

​

    // Omitting long name, defaults to name of property, ie "--verbose"

    [Option('b', "verbose", Default = false, HelpText = "Prints all messages to standard output.")]

    public bool Verbose

    {

        get;

        set;

    }

​

    [Option('i', "stdin", Default = false, HelpText = "Read from stdin")]

    public bool stdin

    {

        get;

        set;

    }

​

    [Value(0, MetaName = "offset", HelpText = "File offset.")]

    public long? Offset

    {

        get;

        set;

    }

}