如何在Perl中找到从包中继承的所有包？ [英] How can I find all the packages that inherit from a package in Perl?

问题描述

我有许多不同的网站，我从中下载数据并按摩到其他格式（使用Perl）以便在工作中使用，这些网站都是从一个Perl脚本运行的，如下所示：

 ＃！ / usr / bin / perl 
使用严格; 
 
使用My :: Package1; 
使用My :: Package2; 
 
 my $ p1 = My :: Package1-> new; 
 $ p1->下载; 
 
 my $ p2 = My :: Package2-> new; 
 $ p2->下载; 
  

依此类推。目前，每个 My :: Package 都是自己的包;它不会从基础包或任何东西继承。我打算使用 Moose 重新编写它们，我希望每次添加新软件包时都不必编辑运行下载的Perl脚本，是一种查找从基础包继承的包的方法，然后在循环实例化每个包并进行下载，有点像：

 ＃！ / usr / bin / perl 
使用严格; 
 
我的$ pname（packages_that_inherit_from（My :: Package））{
 my $ package = $ pname-> new; 
 $ package->下载; 
} 
  

它可能或其他东西可能吗？

TIA

解决方案

使用 Moose 的 Class :: MOP 支持你可以找到分配给每个类的子类（在那个时间点）。 / p>

来自 Class :: MOP :: Class docs：

$ metaclass-> subclasses
这将返回此类的所有子类的列表，甚至是间接子类。

$ metaclass-> direct_subclasses
这将返回此类的直接子类列表，其中不包含间接子类。

例如，如果我们构建这些课程：

  {
 package Root; 
使用驼鹿; 
使用namespace :: clean -except => 元; 
 
 sub baz {说'some root thingy'} 
子下载{说从下载。 __PACKAGE__} 
} 
 
 {
包NodeA; 
使用驼鹿; 
扩展'Root'; 
使用namespace :: clean -except => 元; 
子下载{说从下载。 __PACKAGE__} 
} 
 
 {
包NodeA1; 
使用驼鹿; 
扩展'NodeA'; 
使用namespace :: clean -except => 元; 
子下载{说从下载。 __PACKAGE__} 
} 
  

然后以您的示例为基础，我们可以这样做：

 我的$ pname（Root-> new-> meta-> direct_subclasses）{
 my $ package = $ pname->新建; 
 $ package->下载; 
} 
 
＃=> 从NodeA下载
  

以上运行 NodeA->下载。将上面的内容更改为 meta->子类也会运行 NodeA1->下载。

/ I3az /

I have a number of different sites that I download data from and massage into other formats (using Perl) for use at work, that are all run from one Perl script kinda like so:

#! /usr/bin/perl
use strict;

use My::Package1;
use My::Package2;

my $p1 = My::Package1->new;
$p1->download;

my $p2 = My::Package2->new;
$p2->download;

and so on and so forth. At the moment each My::Package is its own package; it doesn't inherit from a base package or anything. I am planning to re-write them using Moose and I was hoping that rather than having to edit the Perl script that runs the download each time a new package is added, there might be a way of finding packages that inherit from a base package, and then in a loop instantiate each and do the downloading, kinda like so:

#! /usr/bin/perl
use strict;

for my $pname (packages_that_inherit_from("My::Package")) {
    my $package = $pname->new;
    $package->download;
}

Is it, or something ilke it, possible?

TIA

解决方案

Using Moose's Class::MOP underpinning you can find the subclasses assigned to each class (at that point in time).

From Class::MOP::Class docs:

$metaclass->subclasses This returns a list of all subclasses for this class, even indirect subclasses.

$metaclass->direct_subclasses This returns a list of immediate subclasses for this class, which does not include indirect subclasses.

So for example if we build these classes:

{
    package Root;
    use Moose;
    use namespace::clean -except => 'meta';

    sub baz      { say 'Some root thingy' }
    sub download { say "downloading from " . __PACKAGE__ }
}

{
    package NodeA;
    use Moose;
    extends 'Root';
    use namespace::clean -except => 'meta';
    sub download { say "downloading from " . __PACKAGE__ }
}

{
    package NodeA1;
    use Moose;
    extends 'NodeA';
    use namespace::clean -except => 'meta';
    sub download { say "downloading from " . __PACKAGE__ }
}

Then using your example as a basis we can do this:

for my $pname ( Root->new->meta->direct_subclasses ) {
    my $package = $pname->new;
    $package->download;
}

# =>  "downloading from NodeA"

So above runs NodeA->download. Changing above to meta->subclasses would also run the NodeA1->download.

/I3az/

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