use strict;
use warnings;

package Hack;

sub slash {
   my $var_ref = do { no strict 'refs'; \${'ExistingPackage::var'} };
   $$var_ref = 'bar';
}


package main;

ExistingPackage->print_it();
Hack->slash();
ExistingPackage->print_it();

##</code><code>##

use strict;
use warnings;

package ExistingPackage;

our $var = 'foo';

sub print_it {
   print("$var\n");
}

1;

##</code><code>##

package ExistingPackage;

$var = 'foo';

sub print_it {
   print("$var\n");
}

1;