gistfile1.txt

use v6;

role Signal {
        has Method @.slots; # a nice list of callbacks (that are methods)
        method connect(Any $sender, Any $rcpt, Method $method){
                @.slots.push([$sender, $rcpt, $method]);
        }
}

multi trait_mod:<is>(Method $m, :$signal!){
        $m does Signal;

        proto handle_call(|$) { * }
        
        multi handle_call {
                for $m.slots -> [$sender, $rcpt, $method] {
                        say $sender.WHAT, $rcpt.WHAT, $method.WHAT;
                        $method($rcpt);
                }
        }

        multi handle_call(|$args){
                say $m.WHAT;
                for $m.slots -> [$sender, $rcpt, $method] {
                        say $sender.WHAT, $rcpt.WHAT, $method.WHAT;
                        $method($rcpt, |$args);
                }
        }

        $m.wrap(&handle_call);
}

multi sub connect($sender, Method $signal, $rcpt, Method $slot){
        (&$signal).connect($sender, $rcpt, $slot);
}

class Button {
        our method pressed is signal { warn "signal fired" }
}

class App {
        our method exit { die "gotta run!" }
}

my Button $btn_exit .= new;
my App $app .= new;

connect($btn_exit, &Button::pressed, $app, &App::exit);
$btn_exit.pressed;