perl – 为什么我的Moo对象继承自非Moo类,为某些模块添加到父包中？

我正在尝试使用 GObject Introspection和 Moo在Perl中创建一个Gtk3应用程序.有一个来自Gtk,Gtk :: applicationwindow的非Moo类,我使用extends’Gtk :: applicationwindow’通过Moo子类化.问题在于,当创建该子类的对象时,它仍然是父类的类型 – 即Gtk :: applicationwindow.

我通过继承自己的非基于Moo的类来尝试相同的事情,并且从这个子类创建的对象具有正确的类型.造成这种差异的原因是什么？

use v5.10;
use strict;
use warnings;

# Import the Gtk classes (non-Moo)
use Glib::Object::Introspection;
Glib::Object::Introspection->setup(basename => 'Gtk',version => '3.0',package => 'Gtk');
Glib::Object::Introspection->setup(basename => 'Gio',version => '2.0',package => 'Gio');

#################################################
{
    # A dummy non-Moo class
    package ClassNonMoo;
    sub new { bless {},shift; }
}

{
    # Moo class extending the dummy class
    package ClassMoo;
    use Moo;

    extends 'ClassNonMoo';

    sub FOREIGNBUILDARGS {
        my ($class,%args) = @_;
        return ($args{app});
    }
}
#################################################

{
    # Moo class extending Gtk::applicationwindow
    package ClassMooGtkAppWin;
    use Moo;

    extends 'Gtk::applicationwindow';

    sub FOREIGNBUILDARGS {
        my ($class,%args) = @_;
        return ($args{app});
    }
}

#################################################

# Create objects of ClassMoo and ClassMooGtkAppWin
sub create_objects {
    my ($app) = @_;

    my $o1 = ClassMoo->new( app => $app );
    my $o2 = ClassMooGtkAppWin->new( app => $app );

    say "o1 = $o1\no2 = $o2";
    # Output:
    # o1 = ClassMoo=HASH(0x2f7bc50)
    # o2 = Gtk::applicationwindow=HASH(0x2f7bd40)
    #
    # Shouldn't o2 be of the type ClassMooGtkAppWin ?

    exit(0);
}

# We can create a Gtkapplicationwindow only after creating a GtkApplication and
# running it. This code just ensures that create_object() is called once the
# application is 'active'.
my $app = Gtk::Application->new('org.test','flags-none');
$app->signal_connect(activate => sub { create_objects($app) });
$app->run();

解决方法

“new”构造函数需要以一种方式编写,以观察调用者的实际类(使用子类化),但它们也可以硬编码它们创建对象的类.

相比：

package MyClass;

# Considerate of subclassing
sub new {
    my $class = shift;
    return bless {},$class;
}

# Doesn't give a shit
sub new {
    my $class = shift;
    return bless {};
}

Glib看起来像是一个围绕C库的XS模块包装器,它可能很难编写类.

您可能只是尝试重新祝福(在构造的对象上再次调用祝福)对象到您的实际子类中.不确定如何使用Moo,但可能在BUILD方法中.

您也可以跳过继承并使用委托.创建一个属性来保存原始的Window对象,然后将所有方法委托给它,除了你自己的子类.

在Moose(不是Moo)中,您可以使用正则表达式执行此操作：
https://metacpan.org/pod/Moose#handles-ARRAY-HASH-REGEXP-ROLE-ROLETYPE-DUCKTYPE-CODE

不知道如何与Moo很好地做到这一点.