package JPI::Common;
use strict;
use warnings;
use CGI;
{
  my $q;

  sub new_cgi {
    $q = CGI->new() unless defined $q;
    return $q;
  }
}
1;

##</code><code>##

package JPI::Test;
use strict;
use warnings;
use JPI::Common;

my $q = JPI::Common->new_cgi();

sub change_value {
  $q->param('test','value changed');
}
1;

##</code><code>##

#!/usr/bin/perl -w
use strict;
use JPI::Common;
use JPI::Test;

my $q = JPI::Common->new_cgi();
$q->param('test','initial value');

print $q->header(),
      'Before: ',
      $q->param('test'),
      "\n";

JPI::Test->change_value();
print 'After: ',
      $q->param('test'),
      "\n";

##</code><code>##

Before: initial value
After: value changed