Perl 6 and Parrot Essentials, Second Edition

Subroutines

You can define ordinary subroutines within a class or role. They cannot be invoked on an object with the $object.methodname syntax and will never pass an implicit invocant argument. They aren’t inherited but can be pulled in with role composition. They’re mainly useful for utility code internal to the class:

class Answer::Young;

has $.answer;
 . . . 
sub is_valid ($value) {
    return 1 if 10 < $value < 42;
}
 . . . 
method set_answer ($new) {
    $.answer = $new if is_valid($new);
}

Subroutines may be exported if the class also functions as a module.