*p2::func = $func;

package p2;

our $x = 100;
func();

##</code><code>##

*p2::func = \$func;

package p2;

our $x = 100;
$func->();

##</code><code>##

#!/usr/bin/perl

use warnings;
use strict;

package p1;

our $x = 1;
my $func = sub { print $_[0],"\n" };

$func->($x);

*p2::func = $func;

package p2;

our $x = 100;
func($x);

##</code><code>##

#!/usr/bin/perl

use warnings;
use strict;

package p1;

our $x = 1;
my $func = sub {
	my $pkg = (caller)[0];
	no strict 'refs';
	print ${"${pkg}::x"},"\n"
};

$func->();

*p2::func = $func;

package p2;

our $x = 100;
func();