package foo;
use strict;
require Exporter;

our @ISA = qw(Exporter);
our @EXPORT = qw( $a, $b );

our $a = 1;
our $b = 2;
1;

package bar;
use strict;
require Exporter;

our @ISA = qw(Exporter);
our @EXPORT = qw( $a, $b );

our $a = 99;
our $b = 7775;
1;

#!/usr/bin/perl
use strict;
use warnings;

use foo;

&a
sub a
{
    do something to $a;
    do something to $b
}