urfave_cli_choices_ext

urfave_cli_choices_ext.go

type CLIChoice struct {
	Choices []string
	Default string
	chosen  string
}

func (c *CLIChoice) Set(value string) error {
	for _, choice := range c.Choices {
		if choice == value {
			c.chosen = value
			return nil
		}
	}
	return fmt.Errorf("%s is not valid. Choices are %s", value, strings.Join(c.Choices, ", "))
}

func (c CLIChoice) String() string {
	if c.chosen == "" {
		return c.Default
	}
	return c.chosen
}

&cli.GenericFlag{Name: "loglevel", Value: &CLIChoice{Choices: []string{"trace", "debug", "info", "warn", "error", "critical"}, Default: "info"}},