sub func(){
  my ($self) = @_;
  foreach my $a (@b){}
  foreach my $a (keys %c){}
 }

##</code><code>##

 sub func(){
  my ($self) = @_;
  my @b = @{$self->{'_class_b'}}
  my %c = %{$self->{'_class_c'}}
  ...
 }