my $name = '(\w[\w-]*\w?)';       # any valid hostname segment
my $nnam = "(($name\\.)*$name)";  # one or more "name" segments

my %domainnames = (
  "$nname\\.com" => 'a commercial domain',
  "$nname\\.edu" => 'an educational institution',
);

##</code><code>##

my $name = qr/(\w[\w-]*\w?)/;      # any valid hostname segment
my $nnam = qr/(($name\.)*$name)/;  # one or more "name" segments

my %domainnames = (
  qr/$nname\.com/ => 'a commercial domain',
  qr/$nname\.edu/ => 'an educational institution',
);

##</code><code>##

my $name = qr/(\w[\w-]*\w?)/;      # any valid hostname segment
my $nnam = qr/(($name\.)*$name)/;  # one or more "name" segments

my @domainnames = (
  { re => qr/$nname\.com/, desc => 'a commercial domain'        },
  { re => qr/$nname\.edu/, desc => 'an educational institution' },
);

##</code><code>##

my $name = qr/(\w[\w-]*\w?)/;      # any valid hostname segment
my $nnam = qr/(($name\.)*$name)/;  # one or more "name" segments

my @domainnames = (
  qr/$nname\.com/ => 'a commercial domain',
  qr/$nname\.edu/ => 'an educational institution',
);

my %domainnames;
foreach (0 .. @domainnames/2-1) {
   $domainnames{$domainnames[$_*2+0]} = {
      re   => $domainnames[$_*2+0],
      desc => $domainnames[$_*2+1],
   };
}