# in Foo.pm
package Foo;
use strict;
use warnings;
use vars qw( $foo $bar );

$bar = 2;
our $baz;

sub print_out {
  ++$foo;
  ++$bar;
  ++$baz;
  print "\$foo: $foo\n\$bar: $bar\n\$baz: $baz\n";
}

1;


# in foo.pl
use strict;
use warnings;

package Foo; $Foo::foo = 7; $Foo::bar = 5; $Foo::baz = 8;
package main;
use Foo;
Foo::print_out();
__END__
% perl foo.pl
$foo: 8
$bar: 6
$baz: 9