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.