How to get indirect access to a class attribute?

[Tom Browder]

Given a class like:

our %attrs = (age=>1,wgt=>2);
class foo { has $.age = rw;}

method a {
  for %attrs.kv -> $k, $v {
     my $aval = self."$k"();  # supposed to work for a method name
     say "attr { $k } has value '{ $aval }'";
  }
}

Question:

1. How can I indirectly refer to the attributes in a method?  The
above doesn't work (with or without the '()').

2. Do I have to write a custom accessor to do so?

Thanks.

Best regards,

-Tom