# Pastebin VJioCxoP
 perl6 -e '


class A {
    has $.xx is rw = 0;
    has &.method-cb is rw = {          
        "default method-cb".say;
        .xx = 3; 
    };
    method do-test () {
        "calling method-cb".say;
        self.&!method-cb();

        $!xx.perl.say;
    }
}

my $a = A.new;

$a.method-cb =  {            
    .xx = 5; 
};

$a.do-test;


'
calling method-cb
5