Add short application description under name on all help screens

[ShadowDancer]

Currently if I type application name help screen does not contain any short description of application. If I use help on windows dir command:

`C:\Users\Example>dir /?
Displays a list of files and subdirectories in a directory.

...help text continues

I think that it's nice way of communicating for user, what this tool does (in few words).

Current output:

>MyApp.exe
MyApp 1.0.0
Copyright (C) 2018 MyApp 

  verb1    Help text for verb 1
  verb2    Help text for verb 2
  help             Display more information on a specific command.
  version          Display version information.

Would be nice output:

>MyApp.exe
MyApp 1.0.0
Utility for mass renaming files
Copyright (C) 2018 MyApp 

  verb1    Help text for verb 1
  verb2    Help text for verb 2
  help             Display more information on a specific command.
  version          Display version information.

I think System.Reflection.AssemblyDescriptionAttribute would be good source of this description.

[PolarGoose]

Currently, as a workaround, you can use Copyright project property like this:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <Copyright>First line. Copyright info if it is needed.
Description of your application. You can use &#xA; to introduce a line break.
Another line of the description.
You can also use some project properties like $(Version)</Copyright>
  </PropertyGroup>

Then you will get the description printed in the beginning.

> YourProgram.exe --help
YourProgram 0.0-dev
First line. Copyright info if it is needed.
Description of your application. You can use
 to introduce a line break.
Another line of the description.
You can also use some project properties like 0.0-dev

[Zhaph]

Better yet, use the help customisation features.

It's a little more involved, especially if you're using the async methods, but fairly straightforward, and allows you to use the Description field (which is now multi-line, at least in .net core apps).

Update your main method:

static async Task Main(string[] args)
{
    var parser = new Parser(with => with.HelpWriter = null);

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

    if (parserResult.Tag == ParserResultType.Parsed)
    {
        await parserResult.WithParsedAsync(YourMethod);
    }
    else
    {
        await parserResult.WithNotParsedAsync(errs => DisplayHelp(parserResult, errs));
    }
}

Then create the following DisplayHelp method:

static Task DisplayHelp<T>(ParserResult<T> result, IEnumerable<Error> errs)
{
    Assembly assembly = Assembly.GetExecutingAssembly();
    string description = assembly.GetCustomAttribute<AssemblyDescriptionAttribute>()?.Description;

    var helpText = HelpText.AutoBuild(result, h =>
    {
        if (!string.IsNullOrEmpty(description))
        {
            // If assembly description isn't null, add it as a line above the options, below the copyright
            h.AddPreOptionsLine(description);
        }

        return HelpText.DefaultParsingErrorsHandler(result, h);
    }, e => e);

    Console.WriteLine(helpText);

    return Task.CompletedTask;
}

If you're not using the async methods you can just chain it all together:

static void Main(string[] args)
{
    var parser = new Parser(with => with.HelpWriter = null);

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

    parserResult.WithParsed(options => YourMethod(options)).WithNotParsed(errs => DisplayHelp(parserResult, errs));
}

This would generate:

> YourProgram.exe --help
YourProgram 0.0.1
Copyright © 2022 Company Name
Description text appears here.
Line breaks are supported as expected

  --help                  Display this help screen.

  --version               Display version information.