#!/usr/bin/perl
# Ivan Novick
# autovivification.pl 
# demonstrate perl's autovivification

use strict;
use warnings;

# x is not defined
my $x = undef;
print "$x\n" if $x;

# autovivification occurs here
# perl will create a hash in memory and assign the address to scalar $x
$x->{'foo'} = 3;

# x now contains to a valid memory address of a HASH
print "$x\n";

# the value 3 should be printed
print "$x->{'foo'}\n";