@[heap]
struct Client {
mut:
	ready_callback   ReadyHandler   = unsafe { nil }
	message_callback MessageHandler = unsafe { nil }
}

struct Ready {}

struct Message {}

type ReadyHandler = fn (mut c Client, msg &Ready)

type MessageHandler = fn (mut c Client, msg &Message)

fn (mut client Client) on[T](event string, handler fn (mut c Client, msg &T)) {
	$if T is Ready {
		if event == 'ready' {
			client.ready_callback = handler
		}
	} $else $if T is Message {
		if event == 'message_create' {
			client.message_callback = handler
		}
	}
}

fn on_ready(mut _client Client, _message &Ready) {}

fn on_message(mut _client Client, _message &Message) {}

fn main() {
	mut client := &Client{}
	client.on[Ready]('ready', on_ready)
	client.on[Message]('message_create', on_message)
}