Request/Response Trace

override_attribute.pl

# impossible
package Trace {
    use Moose::Role;
    has trace => (
        isa => 'TraceObject',
        is  => 'ro',
    );
}

package Request {
    with 'Trace';
    has '+trace' => (
       is => 'rw',
       traits => ['SetOnce'],
    );
}

package Response {
     with 'Trace';
}

# Possible
package Message {
    use Moose;
    has trace => (
        isa => 'TraceObject',
        is  => 'ro',
    );
}

package Request {
    use Moose;
    extends 'Message';
    has '+trace' => (
       is => 'rw',
       traits => ['SetOnce'],
    );
}

package Response {
     use Moose;
     extends 'Message';
}