(my $spec_file     = shift) or die $syntax;
(my $data_in_file  = shift) or die $syntax;
(my $data_out_file = shift) or die $syntax;
# etc...

##</code><code>##

die $syntax unless @ARGV == 5;
my ($spec_file, $data_in_file, $data_out_file, $log_file, $max_errors) = @ARGV;

##</code><code>##

my ($spec_file, $data_in_file, $data_out_file, $log_file, $max_errors) = @ARGV;
die $syntax unless defined $max_errors;