# Perl 5
sub get_foo {
  my $self = shift;

  my $ret = $self->{foo};
  return lc $ret; # always normalize
} 

sub set_foo {
   my ($self, $to) = @_;

   $to =~ s/\s+$//; # strip whitespace at the end
   $self->{foo} = $to;
}

# Perl 6:
has $:foo;
sub foo() is rw {
  return new Proxy:
    FETCH => { lc $:foo },
    STORE => -> $to is copy {
      $to ~~ s/\s+$//;
      $:foo = $to;
    };
}
# And then:
say $obj.foo;
$obj.foo = "...";
# Notice: Standard assignment syntax!
# Assignments should look line assingments, not like method calls