ch08.006_best

Perl Best Practices the source code

##############################################################################
##   Code fragment (Recommended) from Chapter 8 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;

Readonly my $EMPTY_STR => q{};

sub rand_text {
    return join $EMPTY_STR, map { int rand 100 } 1..10_000;
}

print "Building scripts (this may take a while)...\n";
my @scripts = map { rand_text() } 1..300;

my $start = time;

use Digest::SHA qw( sha512 );

# Sort by SHA512 digest of scripts
# (optimized with the Schwartzian Transform)

my @sorted_scripts 
    = map  { $_->[0] }                 # 3. Extract only scripts
      sort { $a->[1] cmp $b->[1] }     # 2. Sort on digests
      map  { [$_, sha512($_)] }        # 1. Precompute digests, store with scripts
           @scripts;


print "Took: ", time-$start, " sec\n";