假设我有一个包含一堆基于Moose的类的代码库，我希望它们都使用一组通用的MooseX::*扩展模块。但我不希望每个基于 Moose 的课程都必须像这样开始：
package My::Class;
use Moose;
use MooseX::Aliases;
use MooseX::HasDefaults::RO;
use MooseX::StrictConstructor;
...
相反，我希望每节课都像这样开始：
package MyClass;
use My::Moose;
并让它与上述完全等价。
我第一次尝试实现这一点是基于Mason::Moose ( source ) 使用的方法：
package My::Moose;
use Moose;
use Moose::Exporter;
use MooseX::Aliases();
use MooseX::StrictConstructor();
use MooseX::HasDefaults::RO();
use Moose::Util::MetaRole;
Moose::Exporter->setup_import_methods(also => [ 'Moose' ]);
sub init_meta {
my $class = shift;
my %params = @_;
my $for_class = $params{for_class};
Moose->init_meta(@_);
MooseX::Aliases->init_meta(@_);
MooseX::StrictConstructor->init_meta(@_);
MooseX::HasDefaults::RO->init_meta(@_);
return $for_class->meta();
}
但是这种方法不被 irc.perl.org 上 #moose IRC 频道中的人们推荐，而且它并不总是有效，具体取决于MooseX::*模块的组合。例如，尝试使用My::Moose上面的类来制作My::Class这样的：
package My::Class;
use My::Moose;
has foo => (isa => 'Str');
加载类时导致以下错误：
Attribute (foo) of class My::Class has no associated methods (did you mean to provide an "is" argument?)
at /usr/local/lib/perl5/site_perl/5.12.1/darwin-2level/Moose/Meta/Attribute.pm line 1020.
Moose::Meta::Attribute::_check_associated_methods('Moose::Meta::Class::__ANON__::SERIAL::2=HASH(0x100bd6f00)') called at /usr/local/lib/perl5/site_perl/5.12.1/darwin-2level/Moose/Meta/Class.pm line 573
Moose::Meta::Class::add_attribute('Moose::Meta::Class::__ANON__::SERIAL::1=HASH(0x100be2f10)', 'foo', 'isa', 'Str', 'definition_context', 'HASH(0x100bd2eb8)') called at /usr/local/lib/perl5/site_perl/5.12.1/darwin-2level/Moose.pm line 79
Moose::has('Moose::Meta::Class::__ANON__::SERIAL::1=HASH(0x100be2f10)', 'foo', 'isa', 'Str') called at /usr/local/lib/perl5/site_perl/5.12.1/darwin-2level/Moose/Exporter.pm line 370
Moose::has('foo', 'isa', 'Str') called at lib/My/Class.pm line 5
require My/Class.pm called at t.pl line 1
main::BEGIN() called at lib/My/Class.pm line 0
eval {...} called at lib/My/Class.pm line 0
MooseX ::HasDefaults::RO应该防止这个错误，但它显然没有被要求完成它的工作。注释掉MooseX::Aliases->init_meta(@_);“修复”问题的行，但是a）这是我想要使用的模块之一，并且b）只是进一步强调了这个解决方案的错误。（特别是，init_meta()应该只调用一次。）
所以，我对建议持开放态度，完全忽略了我未能实现这一点的尝试。只要给出在这个问题开始时描述的结果，任何策略都是受欢迎的。
根据@Ether 的回答，我现在有以下内容（这也不起作用）：
package My::Moose;
use Moose();
use Moose::Exporter;
use MooseX::Aliases();
use MooseX::StrictConstructor();
use MooseX::HasDefaults::RO();
my %class_metaroles = (
class => [
'MooseX::StrictConstructor::Trait::Class',
],
attribute => [
'MooseX::Aliases::Meta::Trait::Attribute',
'MooseX::HasDefaults::Meta::IsRO',
],
);
my %role_metaroles = (
role =>
[ 'MooseX::Aliases::Meta::Trait::Role' ],
application_to_class =>
[ 'MooseX::Aliases::Meta::Trait::Role::ApplicationToClass' ],
application_to_role =>
[ 'MooseX::Aliases::Meta::Trait::Role::ApplicationToRole' ],
);
if (Moose->VERSION >= 1.9900) {
push(@{$class_metaroles{class}},
'MooseX::Aliases::Meta::Trait::Class');
push(@{$role_metaroles{applied_attribute}},
'MooseX::Aliases::Meta::Trait::Attribute',
'MooseX::HasDefaults::Meta::IsRO');
}
else {
push(@{$class_metaroles{constructor}},
'MooseX::StrictConstructor::Trait::Method::Constructor',
'MooseX::Aliases::Meta::Trait::Constructor');
}
*alias = \&MooseX::Aliases::alias;
Moose::Exporter->setup_import_methods(
also => [ 'Moose' ],
with_meta => ['alias'],
class_metaroles => \%class_metaroles,
role_metaroles => \%role_metaroles,
);
使用这样的示例类：
package My::Class;
use My::Moose;
has foo => (isa => 'Str');
我收到此错误：
Attribute (foo) of class My::Class has no associated methods (did you mean to provide an "is" argument?) at ...
使用这样的示例类：
package My::Class;
use My::Moose;
has foo => (isa => 'Str', alias => 'bar');
我收到此错误：
Found unknown argument(s) passed to 'foo' attribute constructor in 'Moose::Meta::Attribute': alias at ...