1

考虑以下代码示例：

use Moops;

role RoleA
using Moose {
  requires 'm1';
  method m2() {
    $self->m1." World!\n";
  }
}

role RoleB
using Moose {
  has 'm1' => ( accessor => 'm1', is => 'ro', isa => 'Str', default => 'Hello');
}

class ClassA
with RoleB
with RoleA
using Moose {
  method m3() {
    $self->m2();
  }
}

print ClassA->new()->m3();

“编译”失败，因为属性访问器似乎不满足角色请求m1：

$ perl roletest.pl 
'RoleB|RoleA' requires the method 'm1' to be implemented by 'ClassA' at /usr/lib/perl5/site_perl/Moose/Meta/Role/Application/ToClass.pm line 134.
    Moose::Meta::Role::Application::ToClass::check_required_methods('Moose::Meta::Role::Application::ToClass=HASH(0x28b9d00)', 'Moose::Meta::Role::Composite=HASH(0x28c6270)', 'Moose::Meta::Class=HASH(0x28ee7c0)') called at /usr/lib/perl5/site_perl/Moose/Meta/Role/Application.pm line 55
    Moose::Meta::Role::Application::apply('Moose::Meta::Role::Application::ToClass=HASH(0x28b9d00)', 'Moose::Meta::Role::Composite=HASH(0x28c6270)', 'Moose::Meta::Class=HASH(0x28ee7c0)') called at /usr/lib/perl5/site_perl/Moose/Meta/Role/Application/ToClass.pm line 36
    Moose::Meta::Role::Application::ToClass::apply('Moose::Meta::Role::Application::ToClass=HASH(0x28b9d00)', 'Moose::Meta::Role::Composite=HASH(0x28c6270)', 'Moose::Meta::Class=HASH(0x28ee7c0)', 'HASH(0x28e3410)') called at /usr/lib/perl5/site_perl/Moose/Meta/Role.pm line 470
    Moose::Meta::Role::apply('Moose::Meta::Role::Composite=HASH(0x28c6270)', 'Moose::Meta::Class=HASH(0x28ee7c0)') called at /usr/lib/perl5/site_perl/Moose/Util.pm line 163
    Moose::Util::_apply_all_roles('Moose::Meta::Class=HASH(0x28ee7c0)', undef, 'RoleB', 'RoleA') called at /usr/lib/perl5/site_perl/Moose/Util.pm line 99
    Moose::Util::apply_all_roles('Moose::Meta::Class=HASH(0x28ee7c0)', 'RoleB', 'RoleA') called at /usr/lib/perl5/site_perl/Moose.pm line 66
    Moose::with('Moose::Meta::Class=HASH(0x28ee7c0)', 'RoleB', 'RoleA') called at /usr/lib/perl5/site_perl/Moose/Exporter.pm line 409
    Moose::with('RoleB', 'RoleA') called at roletest.pl line 16
    main::BEGIN() called at roletest.pl line 23
    eval {...} called at roletest.pl line 23
BEGIN failed--compilation aborted at roletest.pl line 23.

使用plainMoose并且Moose::Role这有效（如此处所述）。此外，不使用Moose后端也适用于.

我已经尝试切换with语句的顺序无济于事。用方法声明替换属性可以解决问题，但我需要一种方法来指定属性要求。

有没有办法让这个工作？

4

1 回答 1

1

你确定它适用于普通驼鹿吗？因为我已经尝试过了，但它失败了，并显示了一个非常相似的错误消息：

use v5.14;
use strict;
use warnings;

package RoleA {
    use Moose::Role;
    requires 'm1';
    sub m2 {
        my $self = shift;
        $self->m1." World!\n";
    }
}

package RoleB {
    use Moose::Role;
    has 'm1' => ( accessor => 'm1', is => 'ro', isa => 'Str', default => 'Hello');
}

package ClassA {
    use Moose;
    with qw/ RoleB RoleA /;
    sub m3 {
        my $self = shift;
        $self->m2();
    }
}

print ClassA->new()->m3();

Moose（以及测试套件中相应的 TODO 测试用例）中存在许多问题，这些问题围绕角色中的属性在requires其他角色中不令人满意。例如，错误RT#77406是相似的（尽管不相同）。

通过以特定顺序一次一个地手动组合角色来更新，您可以使其工作：

use Moops;

role RoleA using Moose {
  requires 'm1';
  method m2() {
    $self->m1." World!\n";
  }
}

role RoleB using Moose {
  has 'm1' => ( is => 'ro', isa => 'Str', default => 'Hello' );
}

class ClassA using Moose {
  with 'RoleB';
  with 'RoleA';
  method m3() {
    $self->m2();
  }
}

print ClassA->new()->m3();
于 2014-02-03T14:30:04.680 回答