my @names = qw( car carpet pet);

my $goodnames = sub{
  join( '|', 
    map {quotemeta $_->[0] }
    sort { $b->[1] <=> $a->[1] }
    map { [$_, length ] } @_;
  );
};

# later...
s/stuff (??{ $goodnames->(@names) }) stuff//;

##</code><code>##

.