Question

我无法使用MooseX::Declare覆盖已声明的属性。

use MooseX::Declare;

role Person {
has 'name' => (
    is => 'ro',
    isa => 'Str',
    default => 'John',
    );
}

class Me with Person {
has '+name' => (
        default => 'Michael',
    );
}

执行代码报告的错误：

Could not find an attribute by the name of 'name' to inherit from in Me at /usr/lib/perl5/Moose/Meta/Class.pm line 711
Moose::Meta::Class::_process_inherited_attribute('Moose::Meta::Class=HASH(0x2b20628)', 'name', 'default', 'Michael', 'definition_context', 'HASH(0x114fd38)') called at /usr/lib/perl5/Moose/Meta/Class.pm line 694
Moose::Meta::Class::_process_attribute('Moose::Meta::Class=HASH(0x2b20628)', '+name', 'default', 'Michael', 'definition_context', 'HASH(0x114fd38)') called at /usr/lib/perl5/Moose/Meta/Class.pm line 566
Moose::Meta::Class::add_attribute('Moose::Meta::Class=HASH(0x2b20628)', '+name', 'default', 'Michael', 'definition_context', 'HASH(0x114fd38)') called at /usr/lib/perl5/Moose.pm line 79
Moose::has('Moose::Meta::Class=HASH(0x2b20628)', '+name', 'default', 'Michael') called at /usr/lib/perl5/Moose/Exporter.pm line 370
Moose::has('+name', 'default', 'Michael') called at Test.pm line 12
main::__ANON__() called at /usr/share/perl5/MooseX/Declare/Syntax/MooseSetup.pm line 81
MooseX::Declare::Syntax::MooseSetup::__ANON__('CODE(0x2b0be20)') called at Test.pm line 21

这有效，但不是基于角色：

class Person {
has 'name' => (
    is => 'ro',
    isa => 'Str',
    default => 'John',
    );
}

class Me extends Person {
has '+name' => (
    default => 'Michael',
    );
}

使用角色时我的代码出了什么问题？是否有可能覆盖属性行为？

Answer 1

irc.perl.org上的irc用户#moose给出了解决方案：

<phaylon> iirc MX:Declare will consume the roles declared in the block at the end. try with 'Person'; in the class block before the has

所以以下代码现在正在运行：

use MooseX::Declare;

role Person {
  has 'name' => (
    is => 'ro',
    isa => 'Str',
    default => 'John',
  );
}

class Me {
  with 'Person';

  has '+name' => (
    default => 'Michael',
  );
}

非常感谢phaylon。

使用Moose角色时覆盖默认属性

1 个答案: