NAME

MooseX::Object::Pluggable - Make your classes pluggable

VERSION

version 0.0014

SYNOPSIS

    package MyApp;
    use Moose;

    with 'MooseX::Object::Pluggable';

    ...

    package MyApp::Plugin::Pretty;
    use Moose::Role;

    sub pretty{ print "I am pretty" }

    1;

    #
    use MyApp;
    my $app = MyApp->new;
    $app->load_plugin('Pretty');
    $app->pretty;

DESCRIPTION

This module is meant to be loaded as a role from Moose-based classes. It will add five methods and four attributes to assist you with the loading and handling of plugins and extensions for plugins. I understand that this may pollute your namespace, however I took great care in using the least ambiguous names possible.

How plugins Work

Plugins and extensions are just Roles by a fancy name. They are loaded at runtime on demand and are instance, not class based. This means that if you have more than one instance of a class they can all have different plugins loaded. This is a feature.

Plugin methods are allowed to "around", "before", "after" their consuming classes, so it is important to watch for load order as plugins can and will overload each other. You may also add attributes through "has".

Please note that when you load at runtime you lose the ability to wrap "BUILD" and roles using "has" will not go through compile time checks like "required" and "default".

Even though "override" will work, I STRONGLY discourage its use and a warning will be thrown if you try to use it. This is closely linked to the way multiple roles being applied is handled and is not likely to change. "override" behavior is closely linked to inheritance and thus will likely not work as you expect it in multiple inheritance situations. Point being, save yourself the headache.

How plugins are loaded

When roles are applied at runtime an anonymous class will wrap your class and "$self->blessed", "ref $self" and "$self->meta->name" will no longer return the name of your object; they will instead return the name of the anonymous class created at runtime. See "_original_class_name".

Usage

For a simple example see the tests included in this distribution.

Attributes

_plugin_ns

String. The prefix to use for plugin names provided. "MyApp::Plugin" is sensible.

_plugin_app_ns

An ArrayRef accessor that automatically dereferences into array on a read call. By default it will be filled with the class name and its precedents. It is used to determine which directories to look for plugins as well as which plugins take precedence upon namespace collisions. This allows you to subclass a pluggable class and still use its plugins while using yours first if they are available.

_plugin_locator

An automatically built instance of Module::Pluggable::Object used to locate available plugins.

_original_class_name

Because of the way roles apply, "$self->blessed", "ref $self" and "$self->meta->name" will no longer return what you expect. Instead, upon instantiation, the name of the class instantiated will be stored in this attribute if you need to access the name the class held before any runtime roles were applied.

Public Methods

load_plugins @plugins

load_plugin $plugin

Load the appropriate role for $plugin.

Private Methods

There's nothing stopping you from using these, but if you are using them for anything that's not really complicated you are probably doing something wrong.

_role_from_plugin $plugin

Creates a role name from a plugin name. If the plugin name is prepended with a "+" it will be treated as a full name returned as is. Otherwise a string consisting of $plugin prepended with the "_plugin_ns" and the first valid value from "_plugin_app_ns" will be returned. Example

   #assuming appname MyApp and C<_plugin_ns> 'Plugin'
   $self->_role_from_plugin("MyPlugin"); # MyApp::Plugin::MyPlugin

_load_and_apply_role @roles

Require $role if it is not already loaded and apply it. This is the meat of this module.

_build_plugin_app_ns

Automatically builds the _plugin_app_ns attribute with the classes in the class precedence list that are not part of Moose.

_build_plugin_locator

Automatically creates a Module::Pluggable::Object instance with the correct search_path.

BUGS

Holler?

Please report any bugs or feature requests to "bug-MooseX-Object-Pluggable at rt.cpan.org", or through the web interface at <http://rt.cpan.org/Public/Dist/Display.html?Name=MooseX-Object-Pluggable>. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

    perldoc MooseX-Object-Pluggable

You can also look for information at:

AnnoCPAN: Annotated CPAN documentation
<http://annocpan.org/dist/MooseX-Object-Pluggable>
CPAN Ratings
<http://cpanratings.perl.org/d/MooseX-Object-Pluggable>
RT: CPAN's request tracker
<http://rt.cpan.org/NoAuth/Bugs.html?Dist=MooseX-Object-Pluggable>
Search CPAN
<http://search.cpan.org/dist/MooseX-Object-Pluggable>

ACKNOWLEDGEMENTS

#Moose - Huge number of questions
Matt S Trout <mst@shadowcatsystems.co.uk> - ideas / planning.
Stevan Little - EVERYTHING. Without him this would have never happened.
Shawn M Moore - bugfixes

AUTHOR

Guillermo Roditi <groditi@cpan.org>

COPYRIGHT AND LICENSE

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

CONTRIBUTORS

Karen Etheridge <ether@cpan.org>
Shawn M Moore <sartak@gmail.com>
Yuval Kogman <nothingmuch@woobling.org>
Robert Boone <robo4288@gmail.com>
David Steinbrunner <dsteinbrunner@pobox.com>
Todd Hepler <thepler@employees.org>