使用Moose之前修改方法参数与Privacy冲突
使用Moose之前修改方法参数与Privacy冲突
提问于 2017-07-25 01:18:02
作为mentioned earlier today，我尝试在实例的一个方法被调用时设置它的属性。我还希望将此属性设置为私有。正如已经向我指出的，我不能将该属性设置为ro，因为这也会禁止从类内部进行读访问。因此，我现在将其设置为rw，但我已经开始使用MooseX::Privacy模块。因此，我的属性声明如下所示：
has 'grow_params' => (
is => 'rw',
isa => 'HashRef',
traits => [qw/Private/],
);如果我简单地执行如下操作，则可以很好地工作：
sub grow {
my ($self, $params) = @_;
$self->grow_params($params);
}但是，我想做一些参数检查。通过阅读文档，似乎最好的地方是before。然而，当我尝试这样做时，我遇到了问题。
例如，使用before
before 'grow_params' => sub {
my ($self, $params) = @_;
# Setting default value
$params->{'overripe'} = exists $params->{'overripe'} ? $params->{'overripe'} : 0;
# Making sure its boolean
confess "Argument 'overripe' has to be 0 or 1"
unless ($params->{'overripe'} == 0 || $params->{'overripe'} == 1);
};这会导致以下错误：
Attribute grow_params is private at C:/strawberry/perl/site/lib/MooseX/Privacy/Meta/Attribute/Private.pm line 13.(我还尝试将该属性设置为Protected，猜测可能创建了一个子类，但无济于事。)该属性确实是私有的，但我正在尝试从类中修改它，对吗？跟踪如下所示，所以我假设Banana正在尝试实际的设置，或者我错过了什么？
Attribute grow_params is private at c:/strawberry/perl/site/lib/MooseX/Privacy/Meta/Attribute/Private.pm line 13.
MooseX::Privacy::Meta::Attribute::Private::_check_private(Moose::Meta::Class::__ANON__::SERIAL::9=HASH(0x3fd4a00), "Class::MOP::Method::Wrapped", "grow_params", "Banana", "Banana") called at c:/strawberry/perl/site/lib/MooseX/Privacy/Meta/Attribute/Privacy.pm line 31
Banana::grow_params(Banana=HASH(0x25223e8), HASH(0xed97a8)) called at c:/strawberry/perl/site/lib/Class/MOP/Method/Wrapped.pm line 44
Banana::_wrapped_grow_params(Banana=HASH(0x25223e8), HASH(0xed97a8)) called at c:/strawberry/perl/site/lib/Class/MOP/Method/Wrapped.pm line 95
Banana::grow_params(Banana=HASH(0x25223e8), HASH(0xed97a8)) called at C:\xampp\htdocs\grinding\banana\/Banana.pm line 31
Banana::grow(Banana=HASH(0x25223e8), HASH(0xed97a8)) called at run.pl line 16运行你自己的完整代码。
# Banana.pm
package Banana;
use strict;
use warnings;
use Carp qw( confess );
use Moose;
use MooseX::Privacy;
has ['peel', 'edible'] => (
is => 'ro',
isa => 'Bool',
required => 1,
);
has 'color' => (
is => 'ro',
isa => 'Str',
required => 1,
);
has 'grow_params' => (
is => 'rw',
isa => 'HashRef',
traits => [qw/Private/],
);
sub grow {
my ($self, $params) = @_;
$self->grow_params($params);
}
before 'grow_params' => sub {
my ($self, $params) = @_;
# Setting default value
$params->{'overripe'} = exists $params->{'overripe'} ? $params->{'overripe'} : 0;
# Making sure its boolean
confess "Argument 'overripe' has to be 0 or 1"
unless ($params->{'overripe'} == 0 || $params->{'overripe'} == 1);
};
1;
# run.pl
use strict;
use warnings;
use File::Basename qw(fileparse dirname);
use Cwd qw(abs_path);
# Add current directory to @INC
use lib (fileparse(abs_path($0)))[1];
use Banana;
my $chiquita = Banana->new({
peel => 1,
edible => 0,
color => 'green'
});
$chiquita->grow({
size => 'medium',
color => 'yellow'
});回答 1
Stack Overflow用户
回答已采纳
发布于 2017-07-25 03:32:23
如果我们研究一下MooseX::Privacy的实现，更具体地说是MooseX::Privacy::Meta::Attribute::Private v0.05，我们可以看到发生了什么。
sub _check_private {
my ($meta, $caller, $attr_name, $package_name) = @_;
confess "Attribute " . $attr_name . " is private"
unless $caller eq $package_name;
}所以，问题一定是$caller不等于$package_name。我想，这是用Perl术语表达隐私概念的一种方式。
谁是before方法的调用者？我稍微修改了代码，以便在支票之前打印$caller。这就是罪魁祸首：
Class::MOP::Method::Wrapped
这与方法修饰符的实现方式有关(顾名思义)。
在我看来，你的期望是合理的，这是MooseX::Privacy的缺陷，也是它处理MOP生态系统内部工作方式的缺陷。
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/45286468
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