$regex= composeRegex($search);

...

sub composeRegex {
  my ($search, $extra)= @_;

  # you might still un-pack these into local variables for convenience
  my ($regcase, $wholeword, $startverse, $endverse, $checkdelimit, $delimitchars, $useperl, $query)
      = @{$search}{qw( case wholeword startverse endverse flexdelimit delimitchars regex comp )};
  ...
}