- POSIX-style short flag combining.
- Parsed, type-safe flags.
- Parsed, type-safe positional arguments.
- Callbacks per command, flag and argument callbacks.
Kingpin supports command line interfaces like this:
$ chat server <ip>
$ chat [--debug] register [--name <name>] <nick>
$ chat post --channel|-c <channel> [--image <image>] [<text>]From code like this:
var (
chat = kingpin.New("chat", "A command line chat application.")
debug = chat.Flag("debug", "enable debug mode").Default("false").Bool()
server = chat.Command("server", "Server to connect to.")
serverIP = server.Arg("server", "server address").Required().IP()
register = chat.Command("register", "Register a new user.")
registerName = register.Flag("name", "name of user").Required().String()
registerNick = register.Arg("nick", "nickname for user").Required().String()
post = chat.Command("post", "Post a message to a channel.")
postChannel = post.Flag("channel", "channel to post to").Short('c').Required().String()
postImage = post.Flag("image", "image to post").File()
postText = post.Arg("text", "text to post").String()
)
func main() {
switch kingpin.Parse() {
case "register":
// Register user
println(*registerNick)
case "post":
// Post message
if *postImage != nil {
}
if *postText != "" {
}
}
}Kingpin supports both flag and positional argument parsers for converting to
Go types. For example, some included parsers are Int(), Float(),
Duration() and ExistingFile().
A goal of Kingpin is to make extending the supported types simple. As an example, here's the source for the builtin IP parser:
func IP(s Settings) (target *net.IP) {
target = new(net.IP)
s.SetParser(func(value string) error {
if ip := net.ParseIP(value); ip == nil {
return fmt.Errorf("'%s' is not an IP address", value)
} else {
*target = ip
return nil
}
})
return
}If this weren't a builtin parser you would use it like so:
ip = IP(cmd.Flag("ip", "IP address of server.").Required())