use CGI qw(:standard);

$page = param('page');

# do some header stuff here

if ($page eq 'list_products') {
  # deal with listing products
  print "......"
} elsif ($page eq 'view_product') {
  # deal with viewing products
} elsif ($page eq 'edit_product') {
  # deal with editing products
} elsif ($page eq 'save_product') {
  # deal with saving product changes
} else {
  # display a default page
}

# do some footer stuff here

##</code><code>##

if ($page eq 'list_products') {
  list_products();
} elsif ($page eq 'view_product') {
  view_products();
} elsif ($page eq 'edit_product') {
  edit_product();
} elsif ($page eq 'save_product') {
  save_product();
} else {
  start();
}
sub list_products {
  print '...';
}

##</code><code>##

%pages = (
  list_products => \&list_products,
  view_product  => \&view_product,
  edit_product  => \&edit_product,
  save_product  => \&save_product,
  default       => \&start,
);

if ($pages{$page}) {
  $pages{$page}->();
} else {
  $pages{default}->();
}
sub list_products {
  print '...';
}

##</code><code>##

use base qw(CGI::Application);

sub setup {
  my $self = shift;
  $self->run_modes(
    list_products => 'list_products',
    view_product  => 'view_product',
    edit_product  => 'edit_product',
    save_product  => 'save_product',
    start         => 'start',
  );
}

sub list_products {
  my $self = shift;
  return '...';
}

##</code><code>##

use base qw(CGI::Application);
use CGI::Application::Plugin::AutoRunmode;

sub list_products :RunMode {
  my $self = shift;
  return '...';
}