Moose::Cookbook::Extending::Recipe2(3pm)

NAME

Moose::Cookbook::Extending::Recipe2 - Providing a role for the base
object class

SYNOPSIS

package MooseX::Debugging;

use Moose::Exporter;

Moose::Exporter->setup_import_methods(
    base_class_roles => ['MooseX::Debugging::Role::Object'],
);

package MooseX::Debugging::Role::Object;

use Moose::Role;

after 'BUILDALL' => sub {
    my $self = shift;

    warn "Made a new " . ( ref $self ) . " object\n";
};

DESCRIPTION

In this example, we provide a role for the base object class that adds some simple debugging output. Every time an object is created, it spits out a warning saying what type of object it was.

Obviously, a real debugging role would do something more interesting,
but this recipe is all about how we apply that role.

In this case, with the combination of Moose::Exporter and
Moose::Util::MetaRole, we ensure that when a module does
"use MooseX::Debugging", it automatically gets the debugging role
applied to its base object class.

There are a few pieces of code worth looking at more closely.: Moose::Exporter->setup_import_methods(
base_class_roles => ['MooseX::Debugging::Role::Object'],; );
This creates an "import" method in the "MooseX::Debugging" package. Since we are not actually exporting anything, we do not pass "setup_import_methods" any parameters related to exports, but we need to have an "import" method to ensure that our "init_meta" method is called. The "init_meta" is created by "setup_import_methods" for us, since we passed the "base_class_roles" parameter. The generated "init_meta" will in turn call Moose::Util::MetaRole::apply_base_class_roles.

AUTHOR

Dave Rolsky <autarch@urth.org>

COPYRIGHT AND LICENSE

<http://www.iinteractive.com>

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

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