| Moose::Cookbook::Legacy::Debugging_BaseClassReplacement - phpMan
Moose::Cookbook::Legacy::DebuggUserBCMoose::Cookbook::Legacy::Debugging_BaseClassReplacement(3pm)
NAME
Moose::Cookbook::Legacy::Debugging_BaseClassReplacement - Providing an alternate base
object class
VERSION
version 2.1213
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.
AUTHOR
Moose is maintained by the Moose Cabal, along with the help of many contributors. See
"CABAL" in Moose and "CONTRIBUTORS" in Moose for details.
COPYRIGHT AND LICENSE
This software is copyright (c) 2012 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.
AUTHORS
· Stevan Little <stevan.little AT iinteractive.com>
· Dave Rolsky <autarch AT urth.org>
· Jesse Luehrs <doy AT tozt.net>
· Shawn M Moore <code AT sartak.org>
· XXXX XXX'XX (Yuval Kogman) <nothingmuch AT woobling.org>
· Karen Etheridge <ether AT cpan.org>
· Florian Ragwitz <rafl AT debian.org>
· Hans Dieter Pearcey <hdp AT weftsoar.net>
· Chris Prather <chris AT prather.org>
· Matt S Trout <mst AT shadowcat.uk>
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.
perl v5.20.1 Moose::Cookbook::Legacy::Debugging_BaseClassReplacement(3pm)
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