我在Moose类中有一个类属性,但我希望它在覆盖父类值的子类方面像
Class::Data::Inheritable一样工作.也就是说,子类继承父级的值,直到在子类上调用setter,此时值变为不同.例如
#!/usr/bin/perl
use warnings;
use strict;
{
package Foo;
use Moose;
use MooseX::ClassAttribute;
class_has Item => ( is => 'rw' );
}
{
package Bar;
use Moose;
extends 'Foo';
}
Foo->Item(4);
# This prints "4,4" as expected
#
print join( ",",Foo->Item(),Bar->Item() ) . "\n";
Bar->Item(5);
# Would like this to print "4,5",but it prints "5,5"
#
print join( ",Bar->Item() ) . "\n";
获得此效果的最佳方法是什么,使用MooseX::ClassAttribute还是其他方式？对于任何希望从中继承的类数据而言,这似乎是理想的行为.
解决方法
我知道你要求继承,但可能是角色可以帮助你以不同的方式解决你的问题.
试着用一个简单的例子：
#!/usr/local/bin/perl
use strict;
use feature 'say';
{
package Bomb;
use Moose::Role;
sub fuse { say "Bomb explode" }
sub explode { say "Bomb fuse"}
}
{
package Spouse;
use Moose::Role;
sub fuse { say "Spouse explode"}
sub explode { say "Spouse fuse"}
}
{
package PracticalJoke;
use Moose;
with 'Bomb' => { excludes => 'explode' },'Spouse' => { excludes => 'fuse' };
}
my $joke = PracticalJoke->new();
$joke->fuse();
$joke->explode();
通过“排除”,您可以准确控制应该发生的事情.
看看why roles are awsome
以及来自Ovid的幻灯片约inheritance versus roles.