# Serializes an array, a hash or a list which contains only
# strings and undefs. Everything else will be stringified.
sub serialize_string_list {
   return join('|',
      map {
         (defined($_)
            ? do { local $_=$_; s/\^/^1/g; s/\|/^2/g; $_ }
            : '^0'
         )
      } @_
   );
}

sub populate {
    my @array = (...);
    return serialize_string_list @array;
}