# original: /([^(]+)(\([^)]+\))(.*)/

my $not_paren  = "[^(]+";
my $leftparen  = "\\(";
my $rightparen = "\\)";
my $rest       = ".*";

# now reads:
$string =~ /($not_paren)($leftparen$not_paren$rightparen)($rest)/;