helpcolours

README

kong-help-colours

Drop-in colourised --help output for CLIs built with alecthomas/kong. Three colours, no configuration, just clap-style help.

Install

go get github.com/gavincarr/kong-help-colours

Use

import (
    "github.com/alecthomas/kong"
    helpcolours "github.com/gavincarr/kong-help-colours"
)

func main() {
    var cli struct {
        Verbose bool   `short:"v" help:"Enable verbose output."`
        Out     string `short:"o" placeholder:"FILE" help:"Output file."`
    }
    ctx := kong.Parse(&cli,
        kong.Help(helpcolours.Help),
        kong.ShortHelp(helpcolours.ShortHelp), // optional
    )
    _ = ctx
}

Colour scheme

Element	Colour
Section headers (Usage:, Flags:, Arguments:, Commands:, group titles)	yellow
Program name in the usage line; flag tokens (--foo, -f)	green
Placeholders (<FILE>, [OPTIONS], =STRING)	cyan

The scheme is fixed — no options, no configuration. It mirrors clap's defaults so it'll look like every Rust CLI you've used.

When colours are emitted

Colour is enabled when all of:

• NO_COLOR env var is not set (no-color.org)
• Either FORCE_COLOR is set, or stdout is a terminal

When colour is disabled the package delegates straight through to kong.DefaultHelpPrinter — zero overhead, byte-for-byte identical output.

Try it

go run ./cmd/demo --help

Author

Gavin Carr gavin@openfusion.net

License

MIT — see LICENSE.

Documentation

Overview

Package helpcolours adds clap-style colourised --help output to CLIs built with github.com/alecthomas/kong. Wire it in with:

kong.Parse(&cli,
    kong.Help(helpcolours.Help),
    kong.ShortHelp(helpcolours.ShortHelp), // optional
)

Colour is enabled when stdout is a terminal (or FORCE_COLOR is set) and NO_COLOR is unset.

Index

• Variables

Variables

var Help kong.HelpPrinter = func(options kong.HelpOptions, ctx *kong.Context) error {
	return printWithColour(options, ctx, kong.DefaultHelpPrinter)
}

Help is a kong.HelpPrinter that delegates to kong.DefaultHelpPrinter and post-processes the output to inject ANSI colour codes when colour is enabled for ctx.Stdout.

var ShortHelp kong.HelpPrinter = func(options kong.HelpOptions, ctx *kong.Context) error {
	return printWithColour(options, ctx, kong.DefaultShortHelpPrinter)
}

ShortHelp is the equivalent wrapper around kong.DefaultShortHelpPrinter, for use with kong.ShortHelp(...). Kong invokes the short-help printer when a parse error occurs, to print a one-line usage summary plus a "Run 'foo --help' for more information." pointer.