Moose::Cookbook::LegMoose::Cookbook::Legacy::Debugging_BaseClassReplacement(3)NAMEMoose::Cookbook::Legacy::Debugging_BaseClassReplacement - Providing an
alternate base object class
VERSION
version 2.1005
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.
NAME
Moose::Cookbook::Extending::Recipe3 - Providing an alternate base
object class
VERSION
version 2.0402
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.
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) 2013 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 v5.18.1Moose::Cookbook::Legacy::Debugging_BaseClassReplacement(3)
