perl implementation of python's collection.defaultdict

defaultdict.pl

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

{
    package Tie::DefaultDict;
    require Tie::Hash;
    our @ISA = qw(Tie::ExtraHash);

    sub TIEHASH {
        my ($class, $default, %h) = @_;
        my $self = bless [+{%h}, $default], $class;

        return $self;
    }

    sub STORE {
        my ($self, $key, $value) = @_;
        $self->[0]->{$key} = $value;
    }

    sub FETCH {
        my ($self, $key) = @_;

        if (!exists $self->[0]->{$key}) {
            $self->[0]->{$key} = $self->[1]->();
        }

        return $self->[0]->{$key};
    }
}

tie my %link_to, 'Tie::DefaultDict', sub { "fallback" } => (
    google => "www.google.com",
    apple => "www.apple.com",
);

print $link_to{apple};

1;