package Foo;

use strict;
use warnings;

use Exporter;
our @ISA = qw(Exporter);

our $foo = "FOO";
our @EXPORT = qw( $foo );

1;

##</code><code>##

package Client1;
use strict;
use warnings;
use Foo;
1;

##</code><code>##

package Client2;
use strict;
use warnings;
use Foo;
1;

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

use Client1;
use Client2;

print "Client1::foo=", $Client1::foo, "\n";
print "Client2::foo=", $Client2::foo, "\n";

#both variables $Client1::foo and $Client2::foo are just other names for $Foo::foo, 
#so the second assignment wins
$Client1::foo = 'CLIENT1';
$Client2::foo = 'CLIENT2';

print "Client1::foo=", $Client1::foo, "\n";
print "Client2::foo=", $Client2::foo, "\n";

##</code><code>##

Client1::foo=FOO
Client2::foo=FOO
Client1::foo=CLIENT2
Client2::foo=CLIENT2