Question

最初主题已启动here，但我需要一个有效的代码示例，如何使用Moo或Moose正确委派属性。

根据文档，我编写了这段代码来检查：

package Cat;
use Moo;

has 'token' => ( is => 'rw', default => '12345' );
has 'tiger' => ( is => 'rw', default => sub { my $self = shift; Cat::Tiger->new(token => $self->token) }, handles => [ qw(token) ] );

package Cat::Tiger;
use Moo;
extends 'Cat';
# + some additional methods


package main;
use Data::Dumper;

my $cat = Cat->new(token=>'54321');
warn $cat->token;
warn $cat->tiger->token;

但是这段代码会产生错误：

您无法用a覆盖本地定义的方法（令牌）代表团在3.pl第5行

如果我在第5行删除handles => [ qw(token) ]，代码将返回另一个错误：

3.pl第5行子程序“Tiger :: new”的深度递归。

那怎么办？

我需要将Cat::Tiger对象（$cat->tiger->token）的标记设置为与Cat对象（$cat-token）相同，并在每次Cat标记时同步它们对象改变了。

Answer 1

嗯，问题解决了将令牌移动到单独的类并使用MooX::Singleton用于此类：

package Credentials;
use Moo;
with 'MooX::Singleton';
has 'token' => ( is => 'rw', default => '12345' );

package Cat;
use Moo;
has 'credentials' => ( is => 'rw', default => sub { Credentials->instance }, handles => [qw(token)] );
has 'tiger' => ( is => 'rw', default => sub { Cat::Tiger->new(token => shift->token) } );

package Cat::Tiger;
use Moo;
has 'credentials' => ( is => 'rw', default => sub { Credentials->instance }, handles => [qw(token)] );


package main;
use Data::Dumper;
my $cat = Cat->new;
warn $cat->token;
warn $cat->tiger->token;
$cat->token('54321');
warn $cat->token;
warn $cat->tiger->token; # will be also 54321

如果有人知道更好的解决方案，欢迎您提出建议：）

Perl Moose或Moo中的属性委派

1 个答案: