#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

## This shows that if you test a multi-dimensional hash,
## Perl will "auto-vivify" the first dimension in the
## process of checking if the 2nd dimension exists.

my %apps;
$apps{"App1"}{Memory}    = 4;
$apps{"App1"}{Language}  = 'Perl';
$apps{"App1"}{CPU}       = '1.4';
$apps{"App1"}{Cores}     = '2';

print "No App8 Cores\n" if !exists $apps{App8}{Cores};
print Dumper \%apps;

__END__
No App8 Cores
$VAR1 = {
          'App8' => {},  <-- the exists() created this!!!
          'App1' => {
                      'Memory' => 4,
                      'Cores' => '2',
                      'Language' => 'Perl',
                      'CPU' => '1.4'
                    }
        };