use strict; use warnings; use 5.010; # saving some vertical space

package My::Demo;
use Moose;

has 'why_pass_self' => ( is => 'ro',
                         isa => 'Str',
                         default => 'dunno, is this ok?' );

my $self;

sub BUILD {
  my $s = shift;
  $self = $s;
}

sub _kool_func {
  say $self->why_pass_self;
}

sub kool_func_for_users {
  my $self = shift;
  $self->_kool_func;
}

#####################################################################
package main;

use Scalar::Util qw(refaddr);

my $o1 = My::Demo->new;
print "o1 ", refaddr($o1), " at says: ";
$o1->kool_func_for_users;

my $o2 = My::Demo->new(why_pass_self => "That's why!");
print "o2 ", refaddr($o2), " at says: ";
$o2->kool_func_for_users;
print "o1 ", refaddr($o1), " at says: ";
$o1->kool_func_for_users;