Dealing with multiple-inherited constructors in Moose

问题

Greetings,

I'm learning Moose and I'm trying to write a CGI::Application subclass with Moose, which is made difficult by the fact that CGI-App is not based on Moose.

In my other CGI-App subclasses, I like to have a parent class with a setup method that looks at the child class's symbol table and automatically sets up the runmodes. I figure I can use Moose's metaclass facilities to achieve the same thing in a cleaner way. So here is what I have in my parent class:

use MooseX::Declare;

class MyApp::CGI 
extends Moose::Object
extends CGI::Application { 

    method setup { 
        $self->start_mode( 'main' );

        my @methods = map { $_->name } $self->meta->get_all_methods;

        $self->run_modes( map  { /^rm_(.+)$/  => $_ }
                          grep { /^rm_/ }
                          @methods
                        );
    }

}

...and in my child class:

use MooseX::Declare;

class MyApp::CGI::Login 
extends MyApp::CGI { 
    method rm_main { 
        return "it works";
    }
}

I realized that the reason my runmodes were not getting setup properly is because setup is called by the CGI-App constructor, and Moose::Object is sticking its own constructor in my class. I tried to solve this with a method modifier:

around new { 
    $self = $orig->( @_ );
    $self->CGI::Application::new( @_ );
}

This gives me

Can't call method "BUILDARGS" on unblessed reference at ...Moose/Object.pm line 21.

I have a feeling, however, that I'm going about this in completely the wrong way, and Moose has a much better facility for achieving what I want, which I have not as yet discovered.

回答1:

Have you already looked at Moose::Cookbook::Basics::DateTime_ExtendingNonMooseParent and MooseX::NonMoose?

Update: I am not very familiar with Moose and assorted techniques. I was not able to get the modules to compile using MooseX::Declare and MooseX::NonMoose together. However, here is something that seems to work:

Application Base Class

package My::App;

use Moose;
use MooseX::NonMoose;
extends 'CGI::Application';

sub setup {
    my $self = shift;
    $self->start_mode( 'main' );

    $self->run_modes(
        map { $_ = $_->name;
              /^rm_ (?<rm>.+) $/x ? ( $+{rm} => $_ ) : ()
        } $self->meta->get_all_methods
    );
}

"My::App"

Derived Class

package My::Login;
use Moose;
extends 'My::App';

sub rm_main { 'it works!' }

"My::Login"

Script

#!/usr/bin/perl

use strict;
use warnings;

# For testing on the command line
use FindBin qw( $Bin );
use lib $Bin;

use My::Login;

my $app = My::Login->new;

$app->run;

Output

C:\Temp\f> t
Content-Type: text/html; charset=ISO-8859-1

it works!

来源：https://stackoverflow.com/questions/1057661/dealing-with-multiple-inherited-constructors-in-moose

标签

perl

oop

moose

mop

cgiapp