増補改訂版Java言語で学ぶデザインパターン入門
結城 浩
ソフトバンククリエイティブ / ￥ 3,990 ()
通常24時間以内に発送

package Trouble;
use Moose;

has number => ( isa => 'Str', is => 'ro');

sub getNumber {
  my $self = shift;
  return $self->number;
}

sub toString {
  my $self = shift;
  return "[Trouble " . $self->number . "]";
}

package Support;
use Moose::Role;
use Perl6::Say;
requires 'resolve';

has name => (isa => 'Str', is => 'rw', required => 1);
has next => (isa => 'Support', is => 'rw');


sub setNext {
  my ($self, $next) = @_;
  $self->next($next);
  return $next;
}

sub support {
  my ($self, $trouble) = @_;
  if($self->resolve($trouble)) {
    $self->done($trouble);
  }
  elsif(defined($self->next)) {
    $self->next->support($trouble);
  } else {
    $self->fail($trouble);
  }
}

sub toString {
  my $self = shift;
  return "[" . $self->name . "]";
}

sub done {
  my( $self, $trouble ) = @_;
  say $trouble->toString() . " is resolved by " . $self->toString . ".";
}

sub fail {
  my( $self, $trouble ) = @_;
  say $trouble->toString() . " cannnot be resolved.";
}

package NoSupport;
use Moose;
with 'Support';

sub resolve { return 0; }

package LimitSupport;
use Moose;
with 'Support';
has limit => (isa => 'Int', is => 'rw', required => 1);

sub resolve {
  my ($self, $trouble) = @_;
  if($trouble->getNumber() < $self->limit) {
    return 1;
  }
  else {
    return 0;
  }
}

package SpecialSupport;
use Moose;
with 'Support';

has number => (isa => 'Int', is => 'rw', required => 1);

sub resolve {
  my ($self, $trouble) = @_;
  if($trouble->getNumber() == $self->number) {
    return 1;
  }
  else {
    return 0;
  }
}

package OddSupport;
use Moose;
with 'Support';

sub resolve {
  my ($self, $trouble) = @_;
  if($trouble->getNumber() % 2 == 1) {
    return 1;
  }
  else {
    return 0;
  }
}

package main;
use Perl6::Say;
my $alice   = NoSupport->new(name => "Alice");
my $bob     = LimitSupport->new(name => "Bob", limit => 100);
my $charlie = SpecialSupport->new(name => "Charlie", number => 429);
my $diana   = LimitSupport->new(name => "Diana", limit => 200);
my $elmo    = OddSupport->new(name => "Elmo");
my $fred    = LimitSupport->new(name => "Fred", limit => 300);

$alice->setNext($bob)->setNext($charlie)
  ->setNext($diana)->setNext($elmo)->setNext($fred);

for(my $i=0;$i<500;$i+=33){
  $alice->support(Trouble->new( number => $i));
}

実行

[Trouble 0] is resolved by [Bob].
[Trouble 33] is resolved by [Bob].
[Trouble 66] is resolved by [Bob].
[Trouble 99] is resolved by [Bob].
[Trouble 132] is resolved by [Diana].
[Trouble 165] is resolved by [Diana].
[Trouble 198] is resolved by [Diana].
[Trouble 231] is resolved by [Elmo].
[Trouble 264] is resolved by [Fred].
[Trouble 297] is resolved by [Elmo].
[Trouble 330] cannnot be resolved.
[Trouble 363] is resolved by [Elmo].
[Trouble 396] cannnot be resolved.
[Trouble 429] is resolved by [Charlie].
[Trouble 462] cannnot be resolved.
[Trouble 495] is resolved by [Elmo].