Flag hook executed multiple times

[artemklevtsov]

Hi,

I tried to share flag across commands, but flag hook executed for the each defined command.

package main

import (
	"fmt"

	"github.com/alecthomas/kong"
)

var val string

type ValFlag string

func (f ValFlag) AfterApply() error {
	val = string(f)

	fmt.Printf("val=%s; flag=%s\n", val, f)

	return nil
}

type Cmd1 struct {
	Val ValFlag `default:"value1"`
}

func (cmd *Cmd1) Run() error {
	return nil
}

type Cmd2 struct {
	Val ValFlag `default:"value2"`
}

func (cmd *Cmd2) Run() error {
	return nil
}

type CLI struct {
	Cmd1 Cmd1 `cmd:""`
	Cmd2 Cmd2 `cmd:""`
}

func main() {
	var cli CLI

	parser, err := kong.New(
		&cli,
	)
	if err != nil {
		panic(err)
	}

	args := []string{"cmd-1", "--val=value3"}
	cliCtx, err := parser.Parse(args)
	if err != nil {
		panic(err)
	}

	if err := cliCtx.Run(); err != nil {
		cliCtx.FatalIfErrorf(err)
	}
}

Actual behavior:

val=value3; flag=value3
val=value2; flag=value2

Expected behavior:

val=value3; flag=value3

[alecthomas]

What's the issue you're seeing exactly?

[artemklevtsov]

val is overwritten with the cmd-2 val flag default value.

[artemklevtsov]

I use sync.Once as workaround:

var val string

type ValFlag string

var once sync.Once

func (f ValFlag) AfterApply() error {
	once.Do(func() { val = string(f) })

	fmt.Printf("val=%s; flag=%s\n", val, f)

	return nil
}

Output:

val=value3; flag=value3
val=value3; flag=value2

[artemklevtsov]

My real use case is setup global logger options. I don't use global options because a several subcommands not support logging.