#!/usr/bin/env perl

use 5.010;
use strict;
use warnings;

my $cfg = { x => 'cat' };
say 'INITIAL: ', $cfg;

example_sub();
$cfg->{x} = 'mouse';
say 'CHANGE1: ', $cfg;
example_sub();
$cfg = { x => 'rat' };
say 'CHANGE2: ', $cfg;
example_sub();

sub example_sub {
    say cfg_cache()->{x};
}

sub cfg_cache {
    state $cfg = $cfg;
    say 'CACHED:  ', $cfg;
    return $cfg;
}

##</code><code>##

INITIAL: HASH(0x7ff0f8802ee8)
CACHED:  HASH(0x7ff0f8802ee8)
cat
CHANGE1: HASH(0x7ff0f8802ee8)
CACHED:  HASH(0x7ff0f8802ee8)
mouse
CHANGE2: HASH(0x7ff0f8829c38)
CACHED:  HASH(0x7ff0f8802ee8)
mouse

##</code><code>##

sub cfg_cache {
    state $cfg_ref = \$cfg;
    say 'CACHED:  ', $$cfg_ref;
    return $$cfg_ref;
}

##</code><code>##

INITIAL: HASH(0x7fd539802ee8)
CACHED:  HASH(0x7fd539802ee8)
cat
CHANGE1: HASH(0x7fd539802ee8)
CACHED:  HASH(0x7fd539802ee8)
mouse
CHANGE2: HASH(0x7fd539829c38)
CACHED:  HASH(0x7fd539829c38)
rat

##</code><code>##

sub cfg_cache {
    state $cfg_ref = { %$cfg };
    say 'CACHED:  ', $cfg_ref;
    return $cfg_ref;
}

##</code><code>##

INITIAL: HASH(0x7fd88c002ee8)
CACHED:  HASH(0x7fd88c029c50)
cat
CHANGE1: HASH(0x7fd88c002ee8)
CACHED:  HASH(0x7fd88c029c50)
cat
CHANGE2: HASH(0x7fd88c029c38)
CACHED:  HASH(0x7fd88c029c50)
cat