Mooseでデザパタ - Templateパターン

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

# Template パターン
#
# Java言語で学ぶデザインパターンと同様の例題をPerl+Mooseで記述した。
#
# coded by Dann

{

    package AbstractDisplay;    # 抽象クラスAbstractDisplay
    use Moose::Role;
    requires &#39;open&#39;;
    requires &#39;custom_print&#39;;
    requires &#39;close&#39;;

    sub display {
        my $self = shift;
        $self->open;
        for ( 1 .. 5 ) {
            $self->custom_print;
        }
        $self->close;
    }
}

{

    package CharDisplay;
    use Moose;
    use Perl6::Say;
    with &#39;AbstractDisplay&#39;;
    has ch => ( is => &#39;rw&#39;, required => 1 );

    sub open {
        print "<";
    }

    sub custom_print {
        my $self = shift;
        print $self->ch;
    }

    sub close {
        say ">";
    }
}
{

    package StringDisplay;
    use Moose;
    use Perl6::Say;
    use Moose::Autobox;
    with &#39;AbstractDisplay&#39;;
    has stringchr => ( is => &#39;rw&#39;, required => 1 );

    sub open {
        my $self = shift;
        $self->print_line;
    }

    sub custom_print {
        my $self = shift;
        say "|" . $self->stringchr . "|";
    }

    sub close {
        my $self = shift;
        $self->print_line;

    }

    sub print_line {
        my $self = shift;
        my $n    = $self->stringchr->length;
        print "+";
        for ( 1 .. $n ) {
            print "-";
        }
        say "+";
    }
}

sub main {
    my $d1 = CharDisplay->new( ch => "H" );
    my $d2 = StringDisplay->new( stringchr => "Hello, world." );
    my $d3 = StringDisplay->new( stringchr => "こんにちわ。" );
    $d1->display;
    $d2->display;
    $d3->display;
}

main();

Moose的なポイントは

抽象クラスとしてのRole

でしょうか。

Template Methodのように一部が空実装というケースであれば、around modifireを使って実装してもよいでしょう。