Perl - リファレンス入門(ハッシュリファレンス)

開発環境

• OS X Lion - Apple(OS)
• TextWrangler(Text Editor) (BBEditの機能制限無料版、light版)
• 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4章(リファレンス入門),　4.9(練習問題)1、2を解いてみる。

1.

問題の式のうち異なる参照先は1つで、${$ginger[2]}[1]。

2.

やり方の1つ。(「やり方は何通りもある」(TIMTOWTDI(There Is More Than One Way To Do It.)))

コード(TextWrangler)

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

my @gilligan = qw(red_shirt hat lucky_socks water_bottle);
my @skipper = qw(blue_shirt hat jacket preserver sunscreen);
my @professor = qw(sunscreen water_bottle slide_rule batteries radio);
my %all = (
  Gilligan => \@gilligan,
  Skipper => \@skipper,
  Professor => \@professor,
);
check_items_for_all(\%all);

sub check_required_items {
  my $who = shift;
  my $items = shift;
  my @required = qw(preserver sunscreen water_bottle jacket);
  my @missing = ();
  for my $item(@required){
    unless (grep $item eq $_, @$items){
      print "$who is missing $item.\n";
      push @missing, $item;
    }
  }
  if (@missing) {
    print "Adding @missing to @$items for $who.\n";
    push @$items, @missing;
  }
}

sub check_items_for_all{
  my $all = shift;
  for(keys %$all){
    check_required_items($_, $all->{$_});
  }
}

入出力結果(Terminal)

$ ./sample.pl
Gilligan is missing preserver.
Gilligan is missing sunscreen.
Gilligan is missing jacket.
Adding preserver sunscreen jacket to red_shirt hat lucky_socks water_bottle for Gilligan.
Skipper is missing water_bottle.
Adding water_bottle to blue_shirt hat jacket preserver sunscreen for Skipper.
Professor is missing preserver.
Professor is missing jacket.
Adding preserver jacket to sunscreen water_bottle slide_rule batteries radio for Professor.
$