package FileCollector ;

sub new {
  my $class = shift;

  my $s = bless { _files => {},
                  _target_repo   => '',
                  _selected_file => '',
                  _common_dir    => ''}, $class;
  $s->add_resources(@_);
  return $s;
}

sub add_resources {
  my $s = shift;
  ... does stuff, basically like an init subroutine ...
}

package FileParser ;
use parent qw ( FileCollector );


sub new {
  my $class = shift;
  return $class->SUPER::new(shift);
}

sub add_resources {
  my $s = shift;

  $s->SUPER::add_resources(@_);
  $s->{_nonparseable_files} = $s->{_nonparseable_files} || [];
  $s->{_parseable_files}    = $s->{_parseable_files}    || [];
  $s->_test_parsability;
}

package HeaderAnalyzer ;
use parent qw ( FileParser );

sub new {
  my $class = shift;
  return $class->SUPER::new(shift);
}

sub add_resources {
  my $s = shift;

  $s->SUPER::add_resources(@_);
  $s->{_bad_header_files}          = $s->{_bad_header_files}   || [];
  $s->{_blank_header_files}        = $s->{_blank_header_files} || [];
  $s->{_no_header_files}           = $s->{_no_header_files}    || [];
  $s->{_good_header_files}         = $s->{_good_header_files}  || [];
  $s->{_unrec_header_files}        = $s->{_unrec_header_files} || [];
  $s->_analyze_headers;
}

...MORE PACKAGES THAT BUILD THE CHILD-PARENT CLASS CHAIN FURTHER...