my %name : ATTR;

# becomes
use attributes ();
my %name;
attributes::->import(__PACKAGE__, \%name, 'ATTR');

##</code><code>##

sub MODIFY_HASH_ATTRIBUTES {
    my ($package, $referent, @attrs) = @_;
...

##</code><code>##

            if ($getter = _extract_get($config)) {
                no strict 'refs';
                *{$package.'::get_'.$getter} = sub {
                    return $referent->{ID($_[0])};
                }
            }