#!/usr/bin/perl
use v5.10;
use strict;
use warnings;

sub example_sub {
    my $cfg = cfg_cache();
    say $cfg->{x};
}

sub cfg_cache {
    state $cfg = shift;
    return $cfg;
}

my $cfg = { x => "cat"};

cfg_cache($cfg);

## "cat" gets printed
example_sub();

## "mouse" gets printed.
$cfg->{x} = "mouse";
example_sub();

## but if I reset $cfg "mouse" still gets printed
$cfg = { x => "rat"};
example_sub();