Perl Debugged

5.5. Taking the Long Way Around

There's an alternative way of option parsing using the core module Getopt::Long:

use Getopt::Long;
use constant WEB => 1;
use constant SQL => 2;
use constant REG => 4;

my %dbg_flag = (
   WEB => WEB,
   SQL => SQL,
   REG => REG);
my %dbg;

GetOptions(\%dbg, "D=s@");
my $DEBUG = WEB | REG unless $dbg{D};

$DEBUG |= $dbg_flag{$_}
       || die "Unknown debug flag $_\n"
   foreach @{$dbg{D}};

(We've shown only the option-parsing part.) This has a slightly different interface; instead of separating multiple values with commas, we must repeat the -D flag:

% whizzbang.pl -D WEB -D REG
				

(We could also say “-D=WEB -D=REG”.)

Getopt::Long permits many more choices than this, of course. If you have a complex program (particularly one worked ...