public class MyButton : Object {

    public signal void clicked ();

    public void test () {
        clicked ();          // emit signal
    }
}

void handler_c (MyButton source) {
    stdout.printf ("handler C\n");
}

void main () {
    var b = new MyButton ();
    b.clicked.connect ((s) => stdout.printf ("handler A\n"));
    b.clicked.connect ((s) => {
        stdout.printf ("handler B\n");
    });
    b.clicked.connect (handler_c);
    b.test ();
    b.clicked.disconnect (handler_c);
}