#!c:/perl/bin/perl -w
$|++;

use strict;
use CGI::Simple;

my $nodes = {
  index => \&main_index,
  links => \&show_links,
  shop  => \&shopping,
  _err  => \&invalid_node
};

my $node = $q->param('node') || 'index';
$nodes->{ exists $nodes->{$node} ? $node : '_err' }->();

sub main_index   { }
sub show_links   { }
sub shopping     { }
sub invalid_node { }