Perl - オブジェクトのデストラクション(DESTROY, DBMハッシュ, dbmopen)

続・初めてのPerl 改訂版
Randal L. Schwartz
brian d foy, Tom Phoenix 著

開発環境

• OS X Lion - Apple(OS)
• BBEdit - Bare Bones Software, Inc.(Text Editor)
• Script言語:Perl

『続・初めてのPerl 改訂版』(Randal L. Schwartz, brian d foy, Tom Phoenix 著、伊藤 直也、田中 慎司、吉川 英興 監訳、株式会社ロングテール/長尾 高弘 訳、オライリー・ジャパン、2006年、ISBN4-87311-305-9)の12章(オブジェクトのデストラクション),　12.15(練習問題)1.を解いてみる。

その他参考書籍

• プログラミングPerl〈VOLUME1〉
• プログラミングPerl〈VOLUME2〉
• Perlクックブック〈VOLUME1〉
• Perlクックブック〈VOLUME2〉

1.

コード(BBEdit)

sample.pl

#!/usr/bin/env perl
use strict;
use warnings;
use utf8;
use 5.016;

{
    package Animal;
    sub sound {die "動物のsoundを定義し忘れてる!";}
    sub named {
        my $class = shift;
        my $name = shift;
        my $self = {Name => $name, Color => $class->default_color};
        bless $self, $class;
    }
    sub speak {
        my $either =  shift;
        print $either->name, " goes ", $either->sound, "\n";
    }
    sub name {
        my $either = shift;
        ref $either ? $either->{Name} : "an unnamed $either";
    }
    sub default_color {'brown'}
    sub color {
        my $either = shift;
        ref $either ? $either->{Color} : $either->default_color;
    }
    sub set_name {
        my $self = shift;
        $self->{Name} = shift;
    }
    sub set_color {
        my $self = shift;
        $self->{Color} = shift;
    }
}
{
    package Horse;
    our @ISA = qw(Animal);
    sub sound { "neigh" }
}
{
    package RaceHorse;
    our @ISA = qw(Horse);
    dbmopen our %STANDINGS, "standings", 0666
        or die "Can't open standings:$!\n";
    sub DESTROY {
        my $self = shift;
        my $name = $self->name;
        $STANDINGS{$name} = "@$self{qw(wins places shows losses)}";
        $self->SUPER::DESTROY;
    }
    sub named {
        my $self = shift->SUPER::named(@_);
        my $name = $self->name;
        my @standings = split ' ', $STANDINGS{$name} || "0 0 0 0";
        @$self{qw(wins places shows losses)} = @standings;
        $self;
    }
    sub won {
        shift->{wins}++;
    }
    sub lost {
        shift->{losses}++;
    }
    sub showed {
        shift->{shows}++;
    }
    sub placed {
        shift->{places}++;
    }
    sub standings{
        my $self = shift;
        join ", ", map "$self->{$_} $_", qw(wins places shows losses);
    }
}

my $runner = RaceHorse->named('Billy Boy');
$runner->won;
print $runner->name, ' has standings ', $runner->standings, ".\n";

入出力結果(Terminal)

$ ./sample.pl
Billy Boy has standings 1 wins, 0 places, 0 shows, 0 losses.
$ ./sample.pl
Billy Boy has standings 2 wins, 0 places, 0 shows, 0 losses.
$ ./sample.pl
Billy Boy has standings 3 wins, 0 places, 0 shows, 0 losses.
$ ./sample.pl
Billy Boy has standings 4 wins, 0 places, 0 shows, 0 losses.
$

pythonの場合。

コード(BBEdit)

sample.py

#!/usr/bin/env python3.3
#-*- coding: utf-8 -*-

import os, pickle
class Animal:
    name = "Animal"
    sound = "鳴き声"
    color = "brown"
    def __init__(self, name):
        if name:
            self._name = name
        else:
            self._name = Animal.name
        self._sound = Animal.sound
        self._color = Animal.color
    def getName(self):
        return self._name
    def setName(self, name):
        self._name = name
    def getColor(self):
        return self._color
    def setColor(self, color):
        self._color = color
    def speak(self):
        print("{0} goes {1}".format(self._name, self._sound))
    @staticmethod
    def staticSpeak():
        print("{0} goes {1}".format(Animal.name, Animal.sound))
class Horse(Animal):
    name = "Horse"
    sound = "neigh"

class RaceHorse(Horse):
    file_name = 'standings.db'
    def __init__(self, name):
        Animal.__init__(self, name)
        if os.path.isfile(RaceHorse.file_name):
            with open(RaceHorse.file_name, "rb") as f:
                self._standings = pickle.load(f)
        else:
            self._standings = {"wins":0, "places":0, "shows":0, "losses":0}
    def won(self):
        self._standings["wins"] += 1
    def lost(self):
        self._standings["losses"] += 1
    def shows(self):
        self._standings["shows"] += 1
    def placed(self):
        self._standings["places"] += 1
    def standings(self):
        with open(RaceHorse.file_name, 'wb') as f:
            pickle.dump(self._standings, f)
        return ", ".join(map(lambda x: "{0} {1}".format(self._standings[x], x),
            ["wins", "places", "shows", "losses"]))

runner = RaceHorse("Billy Boy")
runner.won()
print("{0} has standings {1}.".format(runner.getName(), runner.standings()))

入出力結果(Terminal)

$ ./sample.py
Billy Boy has standings 1 wins, 0 places, 0 shows, 0 losses.
$ ./sample.py
Billy Boy has standings 2 wins, 0 places, 0 shows, 0 losses.
$ ./sample.py
Billy Boy has standings 3 wins, 0 places, 0 shows, 0 losses.
$ ./sample.py
Billy Boy has standings 4 wins, 0 places, 0 shows, 0 losses.
$