Moose::Cookbook::Legacy::Debugging_BaseClassReplacement - phpMan

NAME
    Moose::Cookbook::Legacy::Debugging_BaseClassReplacement - Providing an
    alternate base object class

VERSION
    version 2.2200

SYNOPSIS
      package MyApp::Base;
      use Moose;

      extends 'Moose::Object';

      before 'new' => sub { warn "Making a new " . $_[0] };

      no Moose;

      package MyApp::UseMyBase;
      use Moose ();
      use Moose::Exporter;

      Moose::Exporter->setup_import_methods( also => 'Moose' );

      sub init_meta {
          shift;
          return Moose->init_meta( @_, base_class => 'MyApp::Base' );
      }

DESCRIPTION
    WARNING: Replacing the base class entirely, as opposed to applying roles
    to the base class, is strongly discouraged. This recipe is provided
    solely for reference when encountering older code that does this.

    A common extension is to provide an alternate base class. One way to do
    that is to make a "MyApp::Base" and add "extends 'MyApp::Base'" to every
    class in your application. That's pretty tedious. Instead, you can
    create a Moose-alike module that sets the base object class to
    "MyApp::Base" for you.

    Then, instead of writing "use Moose" you can write
    "use MyApp::UseMyBase".

    In this particular example, our base class issues some debugging output
    every time a new object is created, but you can think of some more
    interesting things to do with your own base class.

    This uses the magic of Moose::Exporter. When we call
    "Moose::Exporter->setup_import_methods( also => 'Moose' )" it builds
    "import" and "unimport" methods for you. The "also => 'Moose'" bit says
    that we want to export everything that Moose does.

    The "import" method that gets created will call our "init_meta" method,
    passing it "for_caller => $caller" as its arguments. The $caller is set
    to the class that actually imported us in the first place.

    See the Moose::Exporter docs for more details on its API.

USING MyApp::UseMyBase
    To actually use our new base class, we simply use "MyApp::UseMyBase"
    *instead* of "Moose". We get all the Moose sugar plus our new base
    class.

      package Foo;

      use MyApp::UseMyBase;

      has 'size' => ( is => 'rw' );

      no MyApp::UseMyBase;

CONCLUSION
    This is an awful lot of magic for a simple base class. You will often
    want to combine a metaclass trait with a base class extension, and
    that's when this technique is useful.

AUTHORS
    *   Stevan Little <stevan AT cpan.org>

    *   Dave Rolsky <autarch AT urth.org>

    *   Jesse Luehrs <doy AT cpan.org>

    *   Shawn M Moore <sartak AT cpan.org>

    *   יובל קוג'מן (Yuval Kogman) <nothingmuch AT woobling.org>

    *   Karen Etheridge <ether AT cpan.org>

    *   Florian Ragwitz <rafl AT debian.org>

    *   Hans Dieter Pearcey <hdp AT cpan.org>

    *   Chris Prather <chris AT prather.org>

    *   Matt S Trout <mstrout AT cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2006 by Infinity Interactive, Inc.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.