ch09.058_best

Perl Best Practices the source code

##############################################################################
##   Code fragment (Recommended) from Chapter 9 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;

sub _ascertain_server_status {
    return (load=>0.02, users=>7, uptime=>100, name=>'foobar');
}

use Contextual::Return;
 
sub get_server_status {
    my ($server_ID) = @_;
 
    # Acquire server data somehow...
    my %server_data 
        = _ascertain_server_status($server_ID);
 
    # Return different components of that data, depending on call context...
    return (
        LIST    { @server_data{ qw( name uptime load users ) };                   }
        BOOL    { $server_data{uptime} > 0;                                       }
        NUM     { $server_data{load};                                             }
        STR     { "$server_data{name}: $server_data{uptime}, $server_data{load}"; }
        HASHREF { \%server_data;                                                  }
    );
}

my $server_ID;
my $total_users;

# Total users is sum of users on each server...
$total_users += get_server_status($server_ID)->{users};

use Data::Dumper 'Dumper';
warn Dumper [ $total_users ];

my $servers_summary;

# Compile report on all servers...
$servers_summary .= get_server_status($server_ID) . "\n";

use Data::Dumper 'Dumper';
warn Dumper [ $servers_summary ];

my $total_load;

# Total load is sum of individual server loads...
$total_load += get_server_status($server_ID);

use Data::Dumper 'Dumper';
warn Dumper [
    $total_load
];

# In list context, return all the available information...
my ($name, $uptime, $load, $users) = get_server_status($server_ID);

use Data::Dumper 'Dumper';
warn Dumper [
    $name, $uptime, $load, $users,
];