Can't figure out Help() for arg

[ybizeul]

I'm basically trying to document a complex arg with Help() to no avail.

package main

import "github.com/alecthomas/kong"

var CLI struct {
	CmdTest commandWithHelp `cmd:""`
}

type commandWithHelp struct {
	Test argumentWithHelp `arg:"" help:"Test"`
}

type argumentWithHelp struct {
	Test string `arg:""`
}

func (u *argumentWithHelp) Help() string {
	return `Some longer text`
}

func (u *commandWithHelp) Run(ctx *kong.Context) error {
	return nil
}

func main() {

	ctx := kong.Parse(&CLI, kong.ConfigureHelp(kong.HelpOptions{
		Compact: true,
		Summary: false,
	}))
	_ = ctx.Run()
}

❯ go run . cmd-test -h
Usage: kongtest cmd-test <command>

Flags:
  -h, --help    Show context-sensitive help.

Commands:
  cmd-test <test>    Test

1. For some reason, kong thinks that cmd-test has a cmd-test subcommand
2. Long description for test isn't called or displayed

[alecthomas]

What is happening here is that you're accidentally triggering Kong's branching positional arguments.

You're accidentally triggering this because of a misunderstanding of how Kong arguments work. Kong cannot parse a positional argument into a struct unless you implement a custom decoder on the enclosing struct, in this case on argumentWithHelp.

Finally, Help() methods are currently not called for flags/args, which is why the help for argumentWithHelp does not show up.

Here's a full example showing this behaviour.

It would be good if flags/args could use Help(), but in reality it's quite irritating to have to create custom types for every flag/arg that needs extended help.

[ybizeul]

Thanks for your answer, which, I'm sorry to say, I have a hard time understanding !

So, what happened to this from the doc ? :

Finally, any command, or argument type implementing the interface Help() string will have this function called to retrieve more detail to augment the help tag.

Should this be understood as "... any command, or argument type (not positional) implementing ..." ?

I'm just trying to replicate your own code : https://go.dev/play/p/8AVbyaO3E4k which actually exhibits the same issue.

Thanks for your patience

[alecthomas]

I think that Help() is actually used if it's present, but none of the help formatters will use the additional help on flags or args, only on commands, currently.

[ybizeul]

Well none of that makes any sense to me 😅
Thank you for your time, I truly appreciate it !