ch15.061_prob

来自「Perl Best Practices the source code」· 061_PROB 代码 · 共 52 行

##############################################################################
## Code fragment (NOT RECOMMENDED) from Chapter 15 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...
no strict;
use warnings;
use IO::Prompt;
use Carp;
use English qw( -no_match_vars );
use Data::Alias;
use Readonly;

package Dogtag;
use Class::Std::Utils;
{
    # Attributes...
    my %name_of;
    my %rank_of;
    my %serial_num_of;
 
    # The usual inside-out constructor...
    sub new {
        my ($class, $arg_ref) = @_;
 
        my $new_object = bless anon_scalar(), $class;
 
        # Now allocating serial numbers polymorphically...
        $serial_num_of{ident $new_object} =  $class->_allocate_serial_num();
 
        return $new_object;
    }
 
    # Override this method in any derived class that needs a
    # different serial number allocation mechanism...
    sub _allocate_serial_num {
        return new Unique::ID;
    }

}

use Data::Dumper 'Dumper';
warn Dumper [ Dogtag->new() ];

package Unique::ID;

sub new { return 1 }