ch16.033_best

Perl Best Practices the source code

##############################################################################
##   Code fragment (Recommended) from Chapter 16 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;


package Book;
{
    # Declare attribute hashes, and construct a list of references to them
    # (the \(...) applies the \ operator to each element of the list)...
    my @attr_refs = \(
        my %title_of,
        my %author_of,
        my %publisher_of,
        my %year_of,
        my %topic_of,
        my %style_of,
        my %price_of,
        my %rating_of,
        my %sales_of,
    );
 
    # Clean up attributes when object is destroyed...
    sub DEMOLISH {
        my ($self, $ident) = @_;
 
        # Update library information...
        Library->remove($self);
 
        # Clean up attribute hashes...
        for my $attr_ref (@attr_refs) {
            delete $attr_ref->{$ident};
        }
 
        return;
    }
}