module main

pub struct Message {
pub mut:
    text string = 'Init'
    m2   ?&Message
}

pub fn (mut m Message) update_text(new_text string) {
    m.text = new_text
}

pub fn (mut m Message) update_ext_text(new_text string) ? {
    m.m2?.text = new_text
}

type LocalMessageType = Message

interface IMessage {
mut:
    text string
    update_text(new_text string)
}

struct App {
mut:
    message &IMessage
}

pub fn (mut m LocalMessageType) update_text_externally(new_text string) {
    m.text = new_text
}

fn print_message(mut mdef IMessage) {
    if mut mdef is Message {
        mut a := LocalMessageType(*mdef)
        mut b := &LocalMessageType(mdef)
        mut c := LocalMessageType(mdef)

        dump(a)
        dump(b)
        dump(c)
    }
}

fn test_main() {
    mut m2 := &Message{
        text: 'Init External'
    }
    mut mdef := &Message{
        text: 'Init'
        m2:   m2
    }
    mut app := &App{
        message: mdef
    }
    print_message(mut app.message)
}