be-careful-when-using-any-variables-whatsoever.pl

use v5.14;
use strict;
use warnings;

package My::Role
{
	use Moose::Role;
	my $some_val;
	sub has_my {
		my ( $self, $value ) = @_;
		$some_val //= $value;
		return $some_val;
	}
	sub has_our {
		my ( $self, $value ) = @_;
		our $other_val //= $value;
		return $other_val;
	}
}

package Object1
{
	use Moose;
	with 'My::Role';
}

package Object2
{
	use Moose;
	with 'My::Role';
}

my $first  = Object1->new;
my $second = Object2->new;

$first->has_my(7);
say $second->has_my;

$first->has_our(7);
say $second->has_our;