Acme合体で猫-トースト装置をつくる

#perl #acme

makamaka

2010-12-16

(firstly written in Japanese, later in English)

ワタシハ　makamaka　コンゴトモヨロシク・・・

皆さん、猫-トースト装置（バター猫のパラドックス）ってご存じですよね？

A - バターの塗られたトーストを落とすとバターの面が下になって床に落ちる
B - 猫を高いところから落とすと足から着地する
AとBより、猫の背中にバターの塗られた面を上にしたトーストをつけて落とすと永久に床に着地しない

今日はこの猫-トースト装置のAcmeモジュールをつくってみたいと思います。ご用意するものは

猫　1Acme

トースト　1Acme

CPANには猫に関するモジュールがいくつかありますが、本日はAcme::Meowを使いましょう。このモジュール、機能は少ないですがPerl上で子猫が飼える優れもの。

しかしここで残念なお知らせ。CPANにはAcme::Toastが今のところ存在しません。どうする！？

そこでバター云々の話は、いわゆるマーフィーの法則であることを思い出しましょう。そうするとAcme::Murphyがあります。このモジュール、「うまくいかなそうなことはなんであれ、うまくいかない」というマーフィーの法則に従い、useすると必ず失敗（die）する優れもの。

両者を合体させれば、猫-トースト装置になるんじゃないの！？

package Acme::CatToastDevice;

use warnings;
use strict;
use Sex qw( Acme::Murphy Acme::Meow );

our $VERSION = '0.01';

1;

合体には昨年のアドベントカレンダーでも取り上げられたSexを使います。いざAcme合体！

$ perl -I./lib -MAcme::CatToastDevice

MORE! Baby. There! Let's talk about our relationship. YEAH! OOOooooh... Baseball... I thought eight inches was longer than that. OOOooooh... YES! There! OOOooooh... Harder! Recursive inheritance detected in package 'Exporter' at ......../Sex.pm line 71.
BEGIN failed--compilation aborted at lib/Acme/CatToastDevice.pm line 5.
Compilation failed in require.
BEGIN failed--compilation aborted.

エラーが出て失敗。終わった……

悔しいのでAcme::MeowのExport部分をコメントアウトします。

package Acme::Meow;

use warnings;
use strict;

#require Exporter;
#use base qw[ Exporter ];
....

でもよく考えたら（よく考えなくても）Acme::Meow、Acme::Murphyどちらのモジュールも落下に関する機能がありません。そこで、ついでにAcme::CatToastDeviceにfallというメソッドを用意しましょう。呼ぶと無限ループします。

package Acme::CatToastDevice;

use warnings;
use strict;
use Sex qw( Acme::Murphy Acme::Meow );

our $VERSION = '0.01';


sub fall {
    sleep 1 while 1;
}

1;

下記のようなサンプルコードをつくって、再チェレンジ。

use strict;
use Acme::CatToastDevice;

print "This is a cat-toast device!\n";

Acme::CatToastDevice->new->fall;

print "With which side did it fall?\n";

コンゴトモヨロシク・・・

$ perl test.pl
MORE! Does it get bigger? Yes! Does it get bigger? Mmmmmm... Mmmmmm... OOOooooh... YES! Does it get bigger? OOOooooh... Yes!
This is a cat-toast device!

よし、成功！　ずっと着地しない！　……むなしいですね！！！

そんなこんなで、このお正月はあなたもAcme合体で新しいモジュールを創造してみては如何でしょうか。

* ----------------------------------------------------
* English version
* ----------------------------------------------------
TITLE: Make a cat-toast device from Acme-union.

I AM makamaka. NICE TO MEET YOU...

Do you know cat-toast device(Buttered cat paradox)?

A - If you throw a slice of buttered toast into the air it will always fall with the buttered side down.
B - A Cat will always land on its foots.
From A and B, a slice of toast with butter to a cat's back may just not fall. (from uncyclopedia)

I'm going to make this device. Preparation:

cat 1Acme

toast 1Acme

There are some modules about cats on CPAN and I take Acme::Meow today. It has a only few functions but a nice module becase of keeping a kitten in Perl.

Regrettable information: Acme::Toast currently does not exist on CPAN.
Well, we remember the story of a sliec of toast with butter is the so-called Murphy's law. And Acme::Murphy on CPAN. It is a nice module because it always fails (die) to the letter 'if anything can go wrong, it will'.

Those two modules are combined, is it a cat-toast device!?

package Acme::CatToastDevice;

use warnings;
use strict;
use Sex qw( Acme::Murphy Acme::Meow );

our $VERSION = '0.01';

1;

We can use Sex module which was taken in last yeat advent calendar. Let's Acme-unite!

$ perl -I./lib -MAcme::CatToastDevice

MORE! Baby. There! Let's talk about our relationship. YEAH! OOOooooh... Baseball... I thought eight inches was longer than that. OOOooooh... YES! There! OOOooooh... Harder! Recursive inheritance detected in package 'Exporter' at ......../Sex.pm line 71.
BEGIN failed--compilation aborted at lib/Acme/CatToastDevice.pm line 5.
Compilation failed in require.
BEGIN failed--compilation aborted.

Error.... Good-bye!

How disappointing! I comment out lines about Export in Acme::Meow!

package Acme::Meow;

use warnings;
use strict;

#require Exporter;
#use base qw[ Exporter ];
....

But I thought deeply, both Acme::Meow and Acme::Murphy do not have a method relates to fall. So we added fall method into Acme::CatToastDevice. Calling it will cause an infinite loop.

package Acme::CatToastDevice;

use warnings;
use strict;
use Sex qw( Acme::Murphy Acme::Meow );

our $VERSION = '0.01';


sub fall {
    sleep 1 while 1;
}

1;

Retry with the below sample code.

use strict;
use Acme::CatToastDevice;

print "This is a cat-toast device!\n";

Acme::CatToastDevice->new->fall;

print "With which side did it fall?\n";

NICE TO MEET YOU...

$ perl test.pl
MORE! Does it get bigger? Yes! Does it get bigger? Mmmmmm... Mmmmmm... OOOooooh... YES! Does it get bigger? OOOooooh... Yes!
This is a cat-toast device!

Successful! It never land! It's in vain!!!

Well, in this winter vacation, would you like to unite Acme modules into a new Acme.