ch19.027_best

Perl Best Practices the source code

##############################################################################
##   Code fragment (Recommended) from Chapter 19 of "Perl Best Practices"   ##
##     Copyright (c) O'Reilly & Associates, 2005. All Rights Reserved.      ##
##  See: http://www.oreilly.com/pub/a/oreilly/ask_tim/2001/codepolicy.html  ##
##############################################################################


# Standard modules...
use strict;
use warnings;
use IO::Prompt;
use Carp;
use English qw( -no_match_vars );
use Data::Alias;
use Readonly;

my $file;

# This look-up table is handy, but seems to be too bloated...
my %lookup = load_lookup_table($file);
 
# So let's look at how much memory it's using...
use Devel::Size qw( size total_size );
use Perl6::Form;
 
my $hash_mem  = size(\%lookup);           # Storage overheads only
my $total_mem = total_size(\%lookup);     # Overheads plus actual data
my $data_mem  = $total_mem - $hash_mem;   # Data only
 
print form(
    'hash alone: {>>>,>>>,>>} bytes',  $hash_mem,
    'data alone: {>>>,>>>,>>} bytes',  $data_mem,
    '============================',
    'total:      {>>>,>>>,>>} bytes',  $total_mem,
);


sub load_lookup_table {
    return map {$_ => $_} 1..100_000;
}