use Debug (1);

print "This is the program\n";
DEBUG { print "Debugging mode is ON\n"; };
print "Program continues...\n";

##</code><code>##

use Debug (1);
use Debug (0, DBG_SPECIAL);

DEBUG { warn "First type\n"; };
DBG_SPECIAL { warn "Second type\n"; }

##</code><code>##

# This goes in Debug.pm...
package Debug;
use strict;


sub doit (&) {
  my $cref = shift;
  $cref->();
}

sub dontdoit (&) {}

# Export appropriate one as DEBUG

sub import {
  shift;
  my $package = caller || '';
  my $name = $_[1] || 'DEBUG';
  {
    no strict 'refs';
    * { "${package}::$name" } =
      (@_ && $_[0]) ? \&doit : \&dontdoit;
  }
}

1;